The US-brokered agreement to open Gaza's border with Egypt is in danger of collapse just a week after its implementation. Israel is accusing the Palestinians of violating the agreement by allowing 15 exiled terrorists to return to the Strip. They are members of the Islamic militant group Hamas, including one of its founders. Israel says that under the agreement, the Palestinians are supposed to prevent terrorists and weapons from crossing the border. Israeli is threatening to impose economic sanctions and close its borders to Palestinian workers and goods. "If it turns out that we don't have real-time monitoring of who is coming in, Israel has one tool--perhaps the most effective and the most painful--that the crossings between the Gaza Strip and Israel...will become [international] border crossings" and the customs arrangement will be rescinded,” said Prime Minister Ariel Sharon. The current crossings enjoys special trade status.