Opinion for the court filed by Circuit Judge HENDERSON.
The appellant, Paul Wolf (Wolf), filed a Freedom of Information Act (FOIA), 5 U.S.C. §§ 552 et seq., request with the Central Intelligence Agency (CIA or Agency), seeking all records related to Jorge Eliecer Gaitan (Gaitan), a former (and deceased) Colombian politician. After the CIA refused to either confirm or deny the existence of such records, Wolf filed this suit. The CIA subsequently moved for summary judgment on the basis of two FOIA exemptions. In response, Wolf asserted that the Agency waived the exemptions through official acknowledgment of records regarding Gaitan during a 1948 congressional hearing. The district court rejected Wolfs official acknowledgment argument and upheld the CIA’s exemption claims, granting summary judgment to the Agency. Wolf appeals. We affirm the district court except to the extent the Agency officially acknowledged the existence of records before the Congress in 1948; as to the latter, we remand to the district court for further proceedings.
I.
On April 9, 1948, Gaitan, a former Colombian presidential candidate, was assas *373 sinated in Bogota, Colombia. In the wake of his assassination, riots erupted in Bogota which prompted a congressional investigation into the alleged failure of the CIA to predict such unrest. At the hearing, then-CIA Director Admiral R.K. Hillen-koetter (Hillenkoetter) testified that the Agency had in fact predicted the explosive situation brewing in Bogota in 1948. A half century later, Wolf, a historical researcher interested in the life and death of Gaitan, submitted a FOIA request to the CIA seeking “all records about Jorge El-iecer Gaitan.” Reprinted at Appellant’s App. at 2. 1 On September 22, 2000, the CIA issued a Gloma/r response 2 to Wolfs request, neither confirming nor denying the existence of records regarding Gaitan. Following an unsuccessful administrative appeal, Wolf filed suit in April 2001 seeking to compel the CIA to release responsive documents.
Before the district court, the CIA submitted the affidavit of Kathryn Dyer (Dyer Affidavit), the Agency’s Information and Privacy Coordinator, in support of its Glo-mar response. See Dyer Affidavit, reprinted in Appellee’s App. at 28. The Dyer Affidavit explained that official confirmation or denial of the existence of such records might damage both national security, through revelation of intelligence sources or methods, and foreign relations. More specifically, according to the Dyer Affidavit, acknowledgment of such records could disclose the identities of individuals, or categories of individuals, “in which the CIA is interested and upon which it focuses its methods and resources,” thereby allowing foreign intelligence services to more effectively implement countermeasures to CIA information-gathering. Id. at 38-39. Moreover, the Agency asserted that acknowledgment of such records could upset diplomatic relations with foreign governments whose citizens had CIA files. As a consequence, the CIA claimed that the existence of records regarding a foreign national constitutes classified information, making its Glomar response appropriate under FOIA Exemptions 1 and 3. 3
The CIA moved for summary judgment on the strength of the Dyer Affidavit. Wolf responded by filing a cross-motion for summary judgment, contending that the Agency waived the exemptions as a result of Hillenkoetter’s 1948 congressional testimony. During his testimony, Wolf alleged, Hillenkoetter read from official CIA dispatches referencing Gaitan, thereby acknowledging that the CIA had responsive records. Concluding that the Dyer Affidavit explained in reasonably specific detail the danger to intelligence sources and methods if the existence of responsive records were disclosed, the district court held that Exemptions 1 and 3 applied. Because the district court found “no indication from the transcript [of the congressional hearing] that the CIA director was reading from anything more than a prepared statement for the hearing,” Wolf v. CIA, 357 *374 F.Supp.2d 112, 118 (D.D.C.2004), the court held that the Agency did not waive the FOIA exemptions through official acknowledgment of records regarding Gaitan. As a result, the district court granted the CIA’s motion for summary judgment. Wolf now appeals.
II.
The FOIA mandates broad disclosure of government records to the public,
CIA v. Sims,
Under the FOIA, “the burden is on the agency to sustain its action,” 5 U.S.C. § 552(a)(4)(B), and we review
de novo
the agency’s use of a FOIA exemption to withhold documents.
Miller,
III.
The CIA submitted the Dyer Affidavit to support its refusal to either confirm or deny the existence of records pertaining to Jorge Gaitan. The question, then, is whether the existence of Agency records regarding an individual foreign national constitutes information itself protected by either FOIA Exemption 1 or Exemption 3. Proper invocation of, and affidavit support for, either Exemption, standing alone, may justify the CIA’s
Glomar
response.
See Miller,
A.
The Agency justifies its
Glomar
response under Exemption 1 based on the classification criteria of Executive Order 12958.
5
See
Appellee’s Brief at 7; 60 Fed. Reg. 19,825 (Apr. 17, 1995). Executive Order 12958 permits an original classification authority to classify information only if “the original classification authority determines that the unauthorized disclosure of the information reasonably could be expected to result in damage to the national security ... and ... is able to identify or describe the damage.” 60 Fed.Reg. at 19,826 § 1.2(a)(4). Such damage to national security may be claimed only with respect to certain categories of information, specifically information that “concerns ... intelligence sources or methods” or the “foreign relations ... of the United States.”
Id.
at 19, 827 § 1.5(c)-(d). Further, the Supreme Court has recognized the broad sweep of “intelligence sources” warranting protection in the interest of national security.
See Fitzgibbon v. CIA
The Dyer Affidavit asserts that confirmation or denial of the existence of records regarding a foreign national could reasonably be expected to damage national security or foreign relations.
See
Ap-pellee’s App. at 29 (describing “conclusions [Dyer] reached and determinations [she] made”). Consequently, if the Dyer Affidavit plausibly explains the danger, the existence of records
vel non
is proper
*376
ly classified under Executive Order 12958 and justifies the Agency’s invocation of Exemption 1.
See Gardels,
Moreover, the Dyer Affidavit explains that revealing that the CIA maintains records regarding specific foreign nationals could potentially reveal targets of CIA surveillance and, thus, CIA methods. See id. at 38. According to the Agency, the existence or nonexistence of records regarding a foreign national would signal to a foreign intelligence service “the specific persons and areas in which the CIA is interested and upon which it focuses its methods and resources.” Id. Because “[e]very country or group has limited resources[,][t]he disclosure to a potential U.S. intelligence target of the areas and persons of CIA interest would indicate to that target how the CIA is allocating its resources [and][t]herefore, the target may array its counterintelligence and security resources most efficiently to frustrate the CIA.” Id. at 38-39.
In addition to the likely damage to intelligence sources and methods, the Dyer Affidavit outlines the potential harm to foreign relations that would reasonably result from confirming or denying the existence of Agency records about a foreign national. Id. at 41-42. Specifically, Dyer asserts that a foreign government, “whether friend or adversary,” could construe the fact “that the CIA maintains information concerning a covert relationship with a particular foreign national” as evidence “that the CIA has collected intelligence information on or recruited one of its citizens or resident aliens.” Id. at 41. Not surprisingly, the Agency asserts, “[s]uch a perception could be expected to affect adversely U.S. foreign relations with that nation[,] ... especially ... where U.S. allies are concerned.” Id.
In light of the substantial weight accorded agency assertions of potential harm made in order to invoke the protection of FOIA Exemption 1, the Dyer Affidavit both logically and plausibly suffices.
See Gardels,
Moreover, it is logical to conclude that the need to assure confidentiality to a foreign source includes neither confirming nor denying the existence of records even decades after the death of the foreign national. For example, in Fitzgibbon we recognized that the passage of thirty years from the individual’s death failed to negate the necessity of confidentiality because “the Government has a compelling interest in protecting ... the appearance of confidentiality so essential to the effective operation of our foreign intelligence service.” See id. at 763-64 (emphasis in original) (internal quotation omitted). Accordingly, we conclude that the existence or nonexistence of Agency records regarding Gaitan is properly classified information and therefore shielded from disclosure under Exemption 1.
B.
The CIA invokes Exemption 3 as an alternative basis of its
Glomar
response. As noted earlier, Exemption 3 permits an agency to withhold information “specifically exempted from disclosure by statute.” 5 U.S.C. § 552(b)(3). In this regard, the CIA maintains that the existence or nonexistence of records about a foreign national is protected from disclosure under the National Security Act, 50 U.S.C. §§ 401
et seq. See, e.g., Krikorian,
The Supreme Court gives even greater deference to CIA assertions of harm to intelligence sources and methods under the National Security Act.
See Sims,
IV.
Although the CIA properly invoked Exemptions 1 and 3, Wolf asserts that the Agency waived both of them by officially acknowledging the existence of records regarding Gaitan during the 1948 congressional testimony of then-CIA Director Hillenkoetter. Indeed, “when information has been ‘officially acknowledged,’ its disclosure may be compelled even over an agency’s otherwise valid exemption claim.”
Fitzgibbon,
First, the information requested must be as specific as the information previously released. Second, the information requested must match the information previously disclosed____Third, ... the information requested must already have been made public through an official and documented disclosure.
Fitzgibbon,
As a consequence, “a plaintiff asserting a claim of prior disclosure must bear the initial burden of pointing to specific information in the public domain that appears to duplicate that being withheld.”
Afshar,
While FOIA requesters often invoke agency waiver in order to overcome FOIA exemptions, the “official acknowledgment” standard has not yet been applied in the context of a
Glomar
response. In most waiver cases, the inquiry turns on the match between the information requested and the content of the prior disclosure. For instance, in
Fitzgibbon
we rejected the plaintiffs argument that congressional testimony establishing the existence of a CIA station in the 1960s waived Exemption 3’s protection of records about the station in the 1950s because the time period specified in the plaintiffs FOIA request did not match the time period of the prior disclosure.
See
Wolf requested “[a] copy of all records about Jorge Eliecer Gaitan.” Appellee’s App. at 29. The CIA’s Glomar response *379 pinpointed the “specific information at issue” as the existence of Agency “records about Jorge Eliecer Gaitan” vel non. Id. In the Glomar context, then, if the prior disclosure establishes the existence (or not) of records responsive to the FOIA request, the prior disclosure necessarily matches both the information at issue — the existence of records — and the specific request for that information.
Wolf asserts that former CIA Director Hillenkoetter’s testimony before the Congress in 1948 established the existence of Agency “records about” Gaitan.
See
Appellant’s Br. at 23. The district court rejected this contention, concluding that “there is no indication from the transcript that the CIA director was reading from anything more than a prepared statement for the hearing. Moreover, Admiral Hil-lenkotter [sic] never made a specific reference in his testimony to reading from any report or other official document.”
Wolf,
Although Hillenkoetter’s testimony appears to be a prepared statement,
see
Special Subcommittee of the Committee on Expenditures in the Executive Departments (April 15, 1948),
reprinted in
Appellant’s App. at 28,
7
the CIA Director also explicitly “read some excerpts of dispatches relating to the[ ] disturbances” that followed Gaitan’s assassination.
Id.
at 22 (reciting information “obtained by people working for Central Intelligence” in Colombia). The excerpts included references to Gaitan, his followers and their associates in connection with possible communist activity in Colombia.
See id.
at 22-23 (reading report from January 2, 1948 describing “[a] professor at the national university and a member of the Colombian Soviet Cultural Exchange” who “is known to be close to and an advisor of Gaitan”).
8
Further, Hillenkoetter suggested that the dispatches were Agency documents containing sensitive information typically passed on to the Department of State.
Id.
at 28-29 (confirming that dispatches “[were] forwarded to the State Department”). Because the
“specific information at issue,” Public Citizen,
We must now resolve the nature of the information to which Wolf is entitled. The CIA’s official acknowledgment waiver relates only to the existence or nonexistence of the records about Gaitan disclosed by Hillenkoetter’s testimony. As a result, Wolf is entitled to disclosure of that information, namely the existence of CIA records about Gaitan that have been previously disclosed (but not any others).
Cf. Fitzgibbon,
y.
In sum, we affirm the district court’s holding that the existence or nonexistence of records about Gaitan is itself classified information and protected from disclosure by Exemptions 1 and 3 of the FOIA. We reverse the district court, however, to the extent that it held that the existence of Agency records about Gaitan was not officially acknowledged by the CIA in testimony before the Congress in 1948. We therefore remand the case to the district court for proceedings consistent with this opinion.
So ordered.
Notes
. Wolf made a similar request for records of the Federal Bureau of Investigation (FBI), which failed to respond until after Wolf filed suit. That request is not part of this appeal.
. See infra p. 5.
. Exemption 1 permits an agency to withhold "matters” from FOIA disclosure if such matters are "(A) specifically authorized under criteria established by an Executive order to be kept secret in the interest of national defense or foreign policy and (B) are in fact properly classified pursuant to such Executive order." 5 U.S.C. § 552(b)(1). Exemption 3 shields matters "specifically exempted from disclosure by statute ..., provided that such statute (A) requires that the matters be withheld from the public in such a manner as to leave no discretion on the issue, or (B) establishes particular criteria for withholding or refers to particular types of matters to be withheld.” 5 U.S.C. § 552(b)(3).
. Wolf challenges the general concept of a
Glomar
response, claiming that
de novo
review of the Agency's response requires the district court to order the Agency to search for responsive records and to submit a
Vaughn
index.
See
Appellant’s Brief at 9;
Vaughn v. Rosen,
. Executive Order 12958 provides agency heads with original classification authority. See Exec. Order No. 12,958, 60 Fed.Reg. 19,-825, 19,827 § 1.4(a)(2) (Apr. 17, 1995); see also Exec. Order No. 13,292, 68 Fed.Reg. 15,315 (Mar. 25, 2003) (amending, in other respects, Executive Order 12958). Classification authority may also be exercised by subordinate officials to whom such authority is delegated, 60 Fed.Reg. at 19,827 § 1.4(a)(3), by an agency head, id. § 1.4(c)(2)-(3), in writing, id. § 1.4(c)(4). Through an internal Agency memorandum, the Director of the CIA delegated original classification authority to the Director of Information Management (Director). See Admin. Rec. 70-3, Annex A, Original Classification Authorities at 1, 3 (June 3, 1997). Further, the Director chairs the Agency Release Panel (ARP), 32 C.F.R. § 1900.41(c)(1) (2006), which makes final determinations regarding administrative appeals under the FOIA. See 32 C.F.R. § 1900.41(a)-(c)(2). In this case, the ARP, chaired by the Director, determined that the existence or nonexistence of records responsive to Wolf's FOIA request is classified information that would tend to reveal intelligence sources and methods. Appellee's App. at 30-31. Dyer, as Information and Privacy Coordinator, serves as the ARP Executive Secretary. 32 C.F.R. § 1900.41(c)(2). Thus, the Dyer Affidavit reflects personal knowledge, obtained in Dyer's official capacity, regarding the classified nature of information related to the existence or nonexistence of records responsive to Wolf’s FOIA request. Appellee’s App. at 29, 31.
. The structure and responsibilities of the United States intelligence community have undergone reorganization in recent years. As a consequence, the duties of the CIA Director are described as they existed at the time of Wolf's FOIA request in 2000. Under the Intelligence Reform and Terrorism Prevention Act of 2004, Pub.L. No. 108-458, the new Director of National Intelligence is similarly required to "protect intelligence sources and methods from unauthorized disclosure.” 50 U.S.C. § 403 — l(i)(l).
. At one point during the hearing, Representative Clarence Brown asked Hillenkoetter whether he had "conclude[d][his] prepared statement for the record.” Appellant's App. at 28. Hillenkoetter indicated that he had completed his prepared statement, thereby opening the hearing to further questions. Id.
. At oral argument, the CIA did not dispute that the references to Gaitan in Hillenkoet-ter’s testimony constitute "records” about Gaitan within the meaning of the FOIA.
Cf. Tobey v. NLRB,
