In September 1947, when Pakistan applied for membership of the United Nations, Afghanistan was the only country, which voted against its admission. The Afghan representative stated on the occasion in the UN General Assembly: We cannot recognise the North West Frontier [Khyber Pakhtunkhwa] as part of Pakistan, so long as the people of North West Frontier have not been given any opportunity free from any kind of influence. I repeat, free from any kind of influence to determine for themselves whether they wish to be independent or to become part of Pakistan. The negative vote was withdrawn by Afghanistan in October 1947. This hostile attitude of Afghanistan led the legal and treaties wing of our Ministry of Foreign Affairs to prepare a substantive brief on our legal position on the issues of state succession, self-determination, fundamental change in circumstances and duress. The Durand Line Border Agreement was signed at Kabul between the British government and H. H. Amir Abdul Rahman Khan in November 1893. This was subsequently recognised by successive Afghan governments, including Amir Habibullah Khan in 1905; King Amanullah Khan in the Treaty of Peace of Rawalpindi of November 1919; the Anglo-Afghan Treaty of 1921, the Trade Convention of Kabul in June 1923 and King Nadir Shah in May 1930. It is provided in Article 11 of the Convention on Succession of States in respect of Treaties 1978 that a succession of states does not as such affect a boundary established by a treaty, or obligations and rights established by a treaty and relating to the regime of a boundary. Also, Article 62 of the Vienna Convention on the Law of Treaties (1969) excepts a boundary treaty from the operation of the rule of rebus sic-stantibus (fundamental change in circumstances). Furthermore, Article 62 of the Convention on the Law of Treaties between States and International Organisations (1986) provides likewise that a fundamental change of circumstances may not be invoked, as a ground for terminating or withdrawing from a treaty between two or more states and one or more international organisations, if the treaty establishes a boundary. The principle of succession to colonial borders was underlined by the international court in the Burkina Faso vs. Republic of Mali case, as well as by the Arbitration Commissions opinion on Yugoslavia with respect to the status of the former internal boundaries between Serbia on the one hand, and Croatia, Bosnia and Herzegovina on the other, concluded that except where otherwise agreed, the former boundaries become frontiers protected by international law. In addition, Article 11 of the Vienna Convention on Succession of Treaties specifies that a succession of states does not as such affect:  a boundary established by treaty; or  obligations and rights established by a treaty and relating to the regime of a boundary. The international court dealt with succession to boundary treaties generally in the Libya vs. Chad case, where it was declared that once agreed, the boundary stands, for any other approach would vitiate the fundamental principle of the stability of boundaries, the importance of which has been repeatedly emphasised by the court. More particularly, the court emphasised that a boundary established by treaty, thus, achieves a permanence which the treaty itself does not necessarily enjoy. The treaty can cease to be in force without in any way affecting the continuance of boundary - when a boundary has been the subject of agreement, the continued existence of that boundary is not dependent upon the continuing life of the treaty under which the boundary is agreed. On the division of the dominion into two states of India and Pakistan and their attainment of independence, Afghanistan questioned the boundary settlement on the basis of the doctrine of fundamental change of circumstances. The UKs attitude in response to this possibility, as summarised by its materials on succession of states, was as follows: The Foreign Office were advised that the splitting of the former India into two states - India and Pakistan - and the withdrawal of British rule from India had not caused the Afghan Treaty to lapse and it was, hence, still in force. It was, nevertheless, suggested that an examination of the treaty might show that some of provisions being political in nature or relating to continuous exchange of diplomatic missions were in the category of those which did not devolve where a state succession took place. However, any executed clauses such as those providing for the establishment of an international boundary or, rather, that had been done already under executed clauses of the treaty, could not be affected, whatever the position about the treaty itself might be. Afghanistan, on the other hand, contested Pakistans right in the circumstances of the case to invoke the boundary provisions of the 1921 Treaty. Mention was made of a letter from the British representative to Sardar-i-Ala the Afghan Foreign Minister, appended to the 1921 Treaty, which recognised that there were tribes on both sides of the frontier, which were of interest to the Government of Afghanistan. The Afghans also noted Article 11 of the Rawalpindi Treaty of 1919 according to which, the two High Contracting Parties having mutually satisfied themselves each regarding the goodwill of the other, and specially regarding their benevolent intentions towards the tribes resident close to their respective boundaries, hereby undertake each to inform the other in future of any military operations of major importance, which may appear necessary for the maintenance of order among the frontier tribes residing within their respective spheres, before the commencement of such operations. However, both these provisions were relating to the tribes and were not relevant to discussing the boundary issues. Pakistan legal position on the Durand Line was so strong that it could treat the issue as a non-issue. The writer is a retired ambassador.