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."
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50 people plan to sail to Gaza to protest Israel's blockage of the Palestinian area
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Last year, 9 were killed after Israeli forces confronted a similar flotilla
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Sec. of State Clinton calls the plan not "useful," urges Americans not to take part
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An activist say the U.S. is giving Israel the "green light" to attack the flotilla
Clinton  added Thursday that it would be unwise to move toward Israeli waters  and create "a situation in which the  @placeholder have the right to defend  themselves."