And while Israel had hoped to defend its tight blockade of Hamas-ruled Gaza with Monday's high-seas raid, it instead appeared to be hastening the embargo's demise, judging by initial international condemnation.
The pre-dawn commando operation, which killed nine pro-Palestinian activists, was also sure to strengthen Gaza's Islamic militant Hamas rulers at the expense of U.S. allies in the region, key among them Hamas' main rival, Palestinian President Mahmoud Abbas, as well as Egypt and Jordan.
"The attack on a humanitarian mission ... will only further alienate the international community and isolate Israel while granting added legitimacy to Hamas' claim to represent the plight of the Palestinian people," said Scott Atran, an analyst at the University of Michigan.
The Mediterranean bloodshed dealt another blow to the Obama administration's efforts to get peace talks back on track. It raised new questions about one of the pillars of U.S. policy - that Hamas can be left unattended as Washington tries to broker a peace deal between Abbas and Israeli Prime Minister Benjamin Netanyahu.
The raid tested U.S.-Israeli ties that have not yet fully recovered from their most serious dispute in decades, triggered by Israeli construction plans in disputed east Jerusalem.
In the most immediate fallout, the interception of the six-boat flotilla carrying 10,000 tons of supplies for Gaza trained the global spotlight on the blockade of the territory. Israel and Egypt sealed Gaza's borders after Hamas overran the territory in 2007, wresting control from Abbas-loyal forces.
The blockade, under which Israel allows in only essential humanitarian supplies, was intended to squeeze the militants. Instead, it has failed to dislodge Hamas, driven ordinary Gazans deeper into poverty and emerged as a constant source of friction and instability. In trying to shake off the blockade, Hamas intensified rocket fire on Israeli border towns, provoking Israel's three-week military offensive against Gaza 16 months ago.
After the war, the international community remained reluctant to push hard for an end to the blockade, for fear it could prolong the rule of Hamas, branded a terrorist organization by the West.
But after Monday's deadly clash, Israel may find itself under growing pressure to at least ease the blockade significantly.
European diplomats on Monday demanded a swift end to the border closure, while U.S. officials said statements would call for greater assistance to the people of Gaza. The officials spoke on condition of anonymity due to the sensitivity of the situation.
The fate of U.S.-led indirect talks between Israel and the Palestinians was uncertain.
Netanyahu canceled a scheduled Tuesday meeting with President Barack Obama in Washington, and the status of a planned visit to Washington by Abbas next week was not immediately clear.
Abbas temporarily walked away from the negotiations in March, after Israel announced more housing for Jews in traditionally Arab east Jerusalem.
But while the Palestinian leader denounced Monday's ship raid as a "sinful massacre," he signaled he would keep going with the indirect talks. Abbas told senior officials of his Fatah movement and the Palestine Liberation Organization that there is no need to quit since the Palestinians are talking to the U.S. and not to Israel, according to his adviser Mohammed Ishtayeh.
Relations between Abbas and Hamas have become increasingly vitriolic, and extending Hamas rule by lifting the blockade would run counter to Abbas' objectives.
Abbas must now make a credible effort to open Gaza's borders, said Palestinian analyst Hani al-Masri. "Otherwise, he will be viewed as weak or part of the siege and lose the support of his people," al-Masri said.
Israel dismissed the condemnation, saying its forces came under attack when they tried to board one of the Turkish-flagged aid vessels. However, its point of view seemed to fall on deaf ears.
"Militarily, we can feel quite safe, but not regarding our political international standing," said Alon Liel, a former Israeli diplomat posted in Turkey.
Israel also appears close to destroying its relationship with key strategic ally Turkey.
Turkey decided to scrap three military drills involving Israel and withdrawal of its ambassador.
Turkey, NATO's sole Muslim member, established close military relations with Israel in 1996 under U.S. pressure. Today, the Islamic-rooted government's sensitivities about the plight of Muslims anywhere and aspirations to have a say in the Middle East and Europe are reshaping Turkish foreign policy.
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Lee reported from Washington. Associated Press writers Mohammed Daraghmeh in Ramallah, West Bank, and Selcan Hacaoglu in Ankara, Turkey, contributed to this report.
