Since the beginning of the regional turmoil and the regime change in Egypt, there were Egyptian voices speaking of cancelling or reviewing the peace treaty with Israel. Lately, after the terrorist attack in Sinai that killed 16 Egyptian border guards, Mr. Mohamed Gadallah, legal adviser to the president of Egypt, Mohamed Morsy, was quoted saying that the president is studying whether to amend the Camp David accords to ensure Egypt’s “full sovereignty” over Sinai.

Naturally, these expressions raise concern in the Israeli public. However, let us put aside the political implications of these expressions to examine international law: can Egypt legally change or cancel unilaterally its peace treaty with Israel?

The peace treaty between Israel and Egypt has no expiration date nor does it prescribe a procedure for its cancellation by one of the parties. This treaty established the peace between Israel and Egypt on the foundations of a full Israeli withdrawal from the Sinai Peninsula and the Israeli recognition of full Egyptian sovereignty over Sinai. In the same breath, the treaty established security arrangements, essentially creating limited force zones, mainly in Sinai, and deploying an international force to supervise the implementation of these security arrangements.

The peace treaty itself allows the review and amendment of the security arrangements, at the request of a party. However, amendments must be by mutual agreement.

Therefore, Egypt may request that Israel review and amend the security arrangement. Israel should consider such a future request in good faith, as required in the implementation of treaties. It is worth mentioning that in the past, in face of a change in security conditions in the Gaza Strip because of Israeli disengagement from the Gaza Strip in 2005, Israel and Egypt agreed on a new security arrangement. Under this arrangement, Egyptian border-guard forces, on an agreed scale, have deployed on the Egyptian side of the Gaza Strip, where only Egyptian civil police, armed with light weapons, were allowed to deploy under the peace treaty.

This was done without derogation from the treaty. Moreover, media reports suggest that where temporary security needs justify the operation of additional forces, this pinpoint activity is enabled through coordination channels with Israel. For example, publications contend that Egyptian air force attacks against terrorist targets in Sinai, after the terrorist attack mentioned above, were coordinated with Israel.

Egypt can reasonably argue that the security circumstances in Sinai have changed due to the establishment and strengthening of terrorist strongholds in the Sinai by local and foreign organizations. It may well be that taking on the weapons these terrorists possess is not possible using only police forces and light weapons. However, any amendment Egypt may seek in the existing arrangement must be proportional to the new threat in the scale of force, its equipment and duration of deployment.

Egypt should remember that the removal from the border of significant Egyptian military forces that may pose a military threat to Israel was a paramount factor enabling Israel to cut the deal and withdraw from Sinai while preserving its security needs. If negotiation regarding amendment of the security arrangements takes place, Israel too could address circumstances that have changed on the ground. For instance, the flow of illegal migrants through the Egyptian-Israeli border, most of them from Eritrea and Sudan, seeking employment in Israel, is also a new phenomenon not anticipated when the treaty was signed. Israel can seek to establish new security arrangements with Egypt to tackle this problem.

International law determines that even a fundamental change of circumstances which has occurred with regard to those existing at the time of the conclusion of a treaty, and which was not foreseen by the parties, may not be invoked as a ground for terminating or withdrawing from the treaty, unless some exceptional conditions were fulfilled. In any case, international law specifically states that such a cause cannot be grounds to terminate a treaty that establishes a boundary. Egypt cannot hold the territorial gains achieved in the peace treaty while shaking off its obligations under it.