Washington (CNN) -- The U.S. State Department on Friday ramped up its warnings urging Americans not to join other activists in a flotilla, expected to sail soon, aimed at challenging Israel's maritime blockage of the Gaza strip.
According to organizers, the flotilla is meant to commemorate the one-year anniversary of a similar flotilla that resulted in a clash in international waters with Israeli navy commandos that left nine people -- including an American citizen -- dead.
Secretary of State Hillary Clinton told reporters Friday that she didn't think the plan "is useful or productive or helpful to the people of Gaza."
"We have certainly encouraged that American citizens not participate in the flotilla," she said, "and we are urging that all precautions be taken to avoid any kind of confrontation."
Clinton's comments followed an even harsher statement by State Department spokesperson Victoria Nuland, in which she criticized what she called "irresponsible and provocative actions that risk the safety of their passengers."
Last May, the Mavi Marmara -- owned by the Turkish Humanitarian Relief Foundation, or IHH -- and five other ships were on their way to Gaza, carrying humanitarian aid and about 700 activists from various countries, when Israeli soldiers swarmed aboard it.
Despite international condemnation, an independent Israeli commission, led by retired judge Yaakov Turkel, later found that Israeli commandos "acted professionally and in a measured manner in the face of unanticipated violence" when they seized the Gaza-bound aid ship.
In September, the U.N. Human Rights Council found Israeli forces "committed serious violations of international law" in the raid and suggested that six of the civilian deaths were "consistent with ... an arbitrary and summary execution."
Israel called the report "as biased and as one-sided as the body that has produced it."
The U.S. State Department earlier this week issued a travel warning advisting U.S. citizens "against traveling to Gaza by any means, including via sea."
"Previous attempts to enter Gaza by sea have been stopped by Israeli naval vessels and resulted in the injury, death, arrest, and deportation of U.S. citizens," the State Department statement said. "U.S. citizens participating in any effort to reach Gaza by sea should understand that they may face arrest, prosecution, and deportation by the government of Israel."
Ali Abunimah, a blogger for the Electronic Intifada and supporter of the protest, accused Clinton of seeming to "lay the ground -- indeed almost provide a green light -- for an Israeli military attack on the upcoming Gaza Freedom Flotilla."
Activists say the blockade is illegal and has worked to undermine Gaza's already fledgling economy. Israel has promised to block any attempt to break a blockade that they say is important in keeping weapons from being delivered to Gaza.
The protesters said they raised funds to purchase a U.S.-flagged vessel, which they named "The Audacity of Hope," a reference to the best-selling book of the same title by President Barack Obama.
The boat, they claim, will carry 36 passengers, four crew members, and ten journalists. The protesters say they want to "challenge U.S. foreign policy" by providing aid and supplies directly to the citizens of Gaza, in spite of Israel's blockade.
"We encourage all Americans to support our voyage, and to agitate with the US government and public opinion to ensure our safe passage to Gaza," wrote Robert Naiman, policy director at the advocacy group Just Foreign Policy, who said he'll be part of the flotilla.
The State Department counters that, if the activists want to help the citizens of Gaza, there is a better -- and legal -- way to do it.
Victoria Nuland, the department's spokeswoman, told reporters, "We've got to use the channels that are safe, the channels that are going to guarantee that the aid get where it needs to go to the people it's intended for."
Clinton added Thursday that it would be unwise to move toward Israeli waters and create "a situation in which the Israelis have the right to defend themselves."
But these words did not impress Abunimah, who wrote that "in light of Clinton's statements, if any blood is spilled it will not only be on Israeli, but also American hands."