CDL-AD(2006)009 - 26 - 108. Foreign armed forces whose admission has been consented to by the receiving State are, as a rule, not subject to the normal immigration controls and entry formalities applicable to foreign nationals. The NATO-SOFA agreement provides that “members of a force shall be exempted from passport and visa regulations and immigration inspection on entering or leaving the territory of a receiving State. They shall also be exempt from the regulations of the receiving State on the registration and control of aliens”69. This waiver of entry procedures is counterbalanced by the requirement for members of the force, to present on demand, whether on entry or at any time thereafter, identification and an individual or collective movement order certifying the status of the individual as a member of a force70. The receiving State has a discretion whether to require a movement order to be countersigned by its authorised representatives. Exemption from entry formalities is made conditional on compliance with the formalities established by the receiving State relating to the entry and departure of a force or the members thereof. 109. The sending State must have access to the base and, where it has more than one base on the territory of the same State, it must be allowed movement between them. To deny access would amount to a derogation from the grant made by the host State. It is therefore common for military base agreements to authorise the sending State to have access to its forces and to the ports or airfields which it has been accorded in the host State. This authorisation is essential, as in relation to public vessels and aircraft there is no right of access under customary international law. It is, however, often the practice in bilateral treaties for entry to the ports of the receiving State to be subject to “appropriate notification under normal conditions” made to the authorities of the latter71. 110. The sending State does not benefit from an unrestricted freedom of movement within, and overflight of, the receiving State, unless such rights are expressly granted in a base agreement. In any case, the national and international law that is applicable to military bases cannot, and does not claim to, diminish the obligations and responsibilities of the member States of the Council of Europe under human rights treaties. F. Article V of the NATO Treaty72 111. Article V is the core clause of the Washington Treaty, NATO’s founding charter. It states that an armed attack against one Ally shall be considered an attack against them all. In response to an invocation of Article 5, each Ally determines, in consultation with other Allies, how it can best contribute to any action deemed necessary to restore and maintain the security of the North Atlantic area, including by the use of armed force. 112. Article V was first invoked on 12 September 2001 immediately following the 11 September terrorist attacks against the United States. The invocation was initially provisional, pending determination that the attacks were directed from abroad. This was confirmed on 2 69 Article III.1 70 Article III.2 71 This is usual, for instance, in US treaty practice. See John Woodcliffe, “The peacetime use of foreign military installations under modern international law”, Martinus Nijhoff, 1992, p. 144. 72 There is a similar provision in the Treaty on Collective Security of the Commonwealth of Independent States (CIS). Two Council of Europe member States, Russia and Armenia, are currently party to this treaty.