Another confrontation is looming on the high seas off the Palestinian-ruled Gaza Strip, days after Israel's deadly flotilla raid.

Pro-Palestinian activists are sailing another ship with humanitarian supplies toward Gaza to try and break the Israeli blockade. It is expected to arrive soon, though it is not clear precisely when. Organizers say Israel is jamming communications and they have lost contact with the vessel.

On Monday, Israeli commandos stormed a flotilla, killing nine activists on board and sparking international outrage. The ship that is now on its way to Gaza is carrying 11 activists, including a Nobel Peace Prize laureate from Northern Ireland. Israel says this vessel, too, will be intercepted.

Greta Berlin of the Free Gaza Movement says activists will not be intimidated. "This is an act of defiance. So it won't make any difference what Israel does. We are still going to go. We have been threatened. We are not going to be stopped," said Berlin.

Video of Monday's incident shows that when Israeli commandos stormed the flotilla, they were beaten by activists wielding clubs. The military also released photos of dozens of knives that were confiscated from the ships.

U.S. President Barack Obama told CNN late Thursday that he acknowledges Israel's security concerns but still called Monday's Israeli raid tragic.

Berlin says the passengers on the ship approaching now are unarmed. "We like to say we are non-violent, direct-action activists. And that simply means that when there is an injustice we will non-violently resist," said Berlin.

Israel has rejected demands by the United Nations to lift the blockade on Gaza, saying that would enable the ruling Palestinian militant group Hamas to rearm with rockets and missiles. At the same time, officials say Prime Minister Benjamin Netanyahu might ease the blockade to appease international anger. While ships heading to Gaza would be searched, more civilian goods would be allowed in to the enclave.