The Egyptians may only open the border crossing with permission of Israel. At the Israel Ministry of Foreign Affairs site you can read the Israel-Egypt Peace Treaty http://www.mfa.gov.il/MFA/Peace+Process/Guide+to+the+Peace+Process/Israel-Egypt+Peace+Treaty.htm "Article II: The permanent boundary between Egypt and Israel in the recognized international boundary between Egypt and the former mandated territory of Palestine, as shown on the map at Annex II, without prejudice to the issue of the status of the Gaza Strip. The Parties recognize this boundary as inviolable. Each will respect the territorial integrity of the other, including their territorial waters and airspace."
Obama to meet with Jordan's King Abdullah in White House later this month (Reuters)
from the article: U.S. lawmakers to Obama: Press Israel to ease Gaza siege