Israel/Palestine

It belongs to the Palestinian Authority, which represents Palestinian territories.

The negotiations are between two belligerent combatants, not two sovereign states, so the border in question is not an international border. In this case, it is the border that separates the sovereign state of Egypt and a war zone. Hamas has no legal claim to it, and neither does Israel. The entirety of the border between Egypt and the war zone is currently being controlled by IDF, a belligerent party in the conflict between Israel and Hamas. That certainly makes it a border between Israel's armed forces and Egypt, for as long as IDF controls it.

Gaza does not belong to Hamas, yet it is Hamas that makes demands on IDF presence in the Philadelphi corridor. If Bibi's demands are objectionable, so are Hamas'.