Israel is bracing for another attempt to break its blockade on the Palestinian-ruled Gaza Strip.

Israel has appealed to the United Nations to prevent two ships in Lebanon from sailing to Gaza, in defiance of the Israeli blockade. In a letter to the U.N. secretary-general and the Security Council, Israel accused organizers of trying “to incite a confrontation and raise tensions” in the Middle East. The letter called on the Lebanese government “to demonstrate responsibility” and stop the ships from departing.

Regional tensions soared two months ago, after Israeli commandos stormed an aid flotilla trying to break the Gaza blockade. Nine pro-Palestinian activists were killed, sparking international outrage.

Since then, Israel has eased the land blockade, allowing all food and some building supplies into Gaza. Therefore, Israel says the aid ships are an unnecessary provocation.

Government spokesman Mark Regev says any humanitarian aid can be taken to Israeli or Egyptian ports near Gaza and delivered via legal channels over land.

“We’ve initiated a policy where we have a liberalization, where we’ve seen a greater volume of goods enter the Gaza Strip, a greater variety of goods entering the Gaza Strip, the beginning of projects for reconstruction, and I think you’ll see these processes continue,” he said.

Israel says the Lebanese guerrilla group Hezbollah is among the organizers of the aid ships, and it fears armed fighters could be on board.

“I saw the leaders of these Lebanese boats on Hezbollah television, and they’re anything but really interested in the well-being of Palestinians,” said the spokesman. “These people are hard-core extremists.”

Israel maintains the naval blockade to prevent weapons from reaching Hamas, the Islamic militant group that rules Gaza. Critics, like those sending the aid ships, say the blockade is collective punishment of 1.5 million Palestinians.