Christopher J. Le Mon, an ASIL member, is an Associate in the Washington, D.C.
office of Shearman & Sterling LLP, and formerly
served as law clerk to Judges Thomas Buergenthal and Vladlen S. Vereshchetin at
the International Court of Justice.
 A previous ASIL Insight examined the international law implications of North Korea's firing of missiles
over the Sea of Japan. See Frederic L. Kirgis, "North Korea's Missile Firings," ASIL Insight, at
 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water, Aug. 5, 1963,
480 U.N. Treaty Series (U.N.T.S.) 43.
 Comprehensive Nuclear Test-Ban Treaty, opened for signature Sept. 24, 1996, 35 International Legal
Materials (I.L.M.) 1439 (1996).
 See Vienna Convention on the Law of Treaties, art. 38, May 23, 1969, 1155 U.N.T.S. 331 (noting the
possibility that rules set forth in treaties may become binding on third states as rules of customary international law).
 PTBT, art. 1(b). Although, as noted above, North Korea is not a party to the PTBT, its assertion that no
radioactive leakage had occurred from the testing site might be seen as evidence that it desires to be viewed as in
compliance with this requirement of the PTBT.
 See North Sea Continental Shelf (F.R.G./Denmark; F.R.G./Netherlands), 1969 I.C..J. 3, paras. 73-74 (Feb.
20) ("With respect to the other elements usually regarded as necessary before a conventional rule can be considered
to have become a general rule of [customary] international law, it might be that, even without the passage of any
considerable period of time, a very widespread and representative participation in the convention might suffice of
itself, provided it included that of States whose interests were specially affected ?. Although the passage of only a
short period of time is not necessarily, or of itself, a bar to the formation of a new rule of customary international
law on the basis of what was originally a purely conventional rule, an indispensable requirement would be that
within the period in question, short though it might be, State practice, including that of States whose interests are
specially affected, should have been both extensive and virtually uniform in the sense of the provision invoked; and
should moreover have occurred in such a way as to show a general recognition that a rule of law or legal obligation
 Treaty on the Non-Proliferation of Nuclear Weapons, July 1, 1968, 729 U.N.T.S. 161.
 Pronouncements by the State Department have not been entirely consistent. Compare Sally Horn, "NPT
Article X," Statement to the 2005 Review Conference of the Treaty on the Nonproliferation of Nuclear Weapons, at
http://www.state.gov/t/vci/rls/rm/46644.htm (Article X "requir[es] three months notice before withdrawal is
complete"), with State Department, Treaties in Force: A List of Treaties and Other International Agreements of the
United States in Force on January 1, 2006, at 486, available at
The Security Council has maintained a similar path of ambiguity. Compare Statement by the President of
the Security Council, U.N. Doc. S/PRST/2006/41 (Oct. 6, 2006) (referring to North Korea's "obligations" under
the NPT and its "announcement of withdrawal" from the NPT rather than an actual, effective withdrawal); S.C. Res.
1695, para. 10 (same), with S.C. Res. 1695, para. 6 (Security Council strongly urges the DPRK to ... return at an
early date to the Treaty on Non-Proliferation of Nuclear Weapons.") (emphasis added). Cf. UN Dep't for
Disarmament Affairs, "Status of Multilateral Arms Regulation and Disarmament Agreements: NPT,"at
(not listing North Korea as a party to the NPT).
 Frederic L. Kirgis, "ASIL Insight: North Korea's Withdrawal from the Nuclear Nonproliferation Treaty,"
at http://www.asil.org/insights/insigh96.htm (Jan. 2003).
 Nuclear Tests (Austl. v. Fr.), 1974 I.C.J. 253 (Dec. 20); Nuclear Tests (N.Z. v. Fr.), 1974 I.C.J. 457 (Dec.
 Nuclear Tests, para. 46.
 International Law Commission, "Guiding Principles applicable to unilateral declarations of States capable
of creating legal obligations," Guiding Principle 1, U.N. Doc. A/61/10, at 367, 368, available at
manifesting the will to be bound may have the effect of creating legal obligations.").
 Nuclear Tests, para. 47.
 Although the Joint Statement was released by all six parties to the talks, it can be considered a declaration
by North Korea to the extent it makes representations on that country's behalf.
 Cf. International Law Commission, "Guiding Principles applicable to unilateral declarations of States
capable of creating legal obligations, with commentaries thereto," Guiding Principle 6, U.N. Doc. A/61/10, at 369,
376, available at http://untreaty.un.org/ilc/texts/instruments/english/commentaries/9_9_2006.pdf (noting a rangeof
acceptable audiences depending on the context of the declaration).
 Nuclear Tests, para. 47.
 Nuclear Tests, para. 44.
 Cf. Frontier Dispute (Burkina Faso v. Mali), 1986 I.C.J. 554, para. 40 (Dec. 22) ("to assess the intentions of
the author of a unilateral act, account must be taken of all the factual circumstances in which the act occurred").
 As an apagogical hypothetical, one can ask what would be the result if the other five parties chose to
abandon the next round of talks, and withdrew their promised enticements. North Korea, having made its
"commitment" in expectation of benefits to be provided by these countries, can hardly be thought to have had the
intention to unilaterally oblige itself to abandon its nuclear weapons programs if such benefits were withdrawn.
 See Christopher J. Le Mon & Rachel S. Taylor, "Security Council Action in the Name of Human Rights:
From Rhodesia to the Congo," 10 U.C. Davis J. Int'l L & Pol. 197, 206-08 (2004), available at
only by the requirement found in Article 24(2) of the Charter that it act according to the purposes and principles of
the United Nations, and by peremptory norms of international law); Christopher J. Le Mon & Rachel S. Taylor,
"Security Council Action in the Name of Human Rights," 11 African Y.B. Int'l L. 263 (2003), available at
 UN Charter, art. 25 ("The Members of the United Nations agree to accept and carry out the decisions of the
Security Council in accordance with the present Charter."); cf. Legal Consequences for States of the Continued
Presence of South Africa in Namibia (South-West Africa) notwithstanding Security Council Resolution 276 (1970)
(Advisory Opinion), 1971 I.C.J. 16, para. 116 ("when the Security Council adopts a decision under Article 25 in
accordance with the Charter, it is for member States to comply with that decision, including those members of the
Security Council which voted against it and those Members of the United Nations who are not members of the
 UN Charter, art. 41 ("The Security Council may decide what measures not involving the use of armed force
are to be employed to give effect to its decisions, and it may call upon the Members of the United Nations to apply
such measures. These may include complete or partial interruption of economic relations and of rail, sea, air, postal,
telegraphic, radio, and other means of communication, and the severance of diplomatic relations.").
 UN Charter, art. 42 ("Should the Security Council consider that measures provided for in Article 41 would
be inadequate or have proved to be inadequate, it may take such action by air, sea, or land forces as may be
necessary to maintain or restore international peace and security. Such action may include demonstrations, blockade,
and other operations by air, sea, or land forces of Members of the United Nations.").
 S.C. Res. 1718, para. 4.
 S.C. Res. 1718, paras. 5-7.
 S.C. Res. 1718, para. 8.
 S.C. Res. 1718, para. 8(f).
 S.C. Res. 1718, para. 8(d).