By Jannat Jalil
BBC correspondent in Washington
The US has reacted to the assassination of the Hamas leader in Gaza, Abdel Aziz al-Rantissi, by saying that Israel has the right to defend itself.
But it also strongly urged Israel to consider carefully the consequences of its actions and has urged all sides in the Middle East dispute to exercise maximum restraint.
The US role has changed from that of mere mediator
This statement from the White House comes just three days after US President George W Bush endorsed the Israeli prime minister's "unilateral disengagement" plan.
The controversial plan is for Israel to pull out of Gaza, but keep Jewish settlements in the West Bank.
Claims of bias
Mr Bush's support represents a historic shift in US policy on the long-running Middle East dispute.
The White House's refusal to condemn the latest killing, saying that Hamas is a terrorist organisation that targets civilians, is likely to be seen by Palestinians as another example of what they perceive as US bias against them.
They have already been angered by Mr Bush's endorsement of Ariel Sharon's plan, saying the Bush administration has made major concessions to Israel on issues which were supposed to have been negotiated with the Palestinian leadership.
Those issues include the right of return for Palestinian refugees and what happens to the Jewish settlements in the West Bank.
Mr Bush insists that he is still committed to the roadmap peace plan which is supposed to lead to the creation of an independent viable Palestinian state.
But some observers say that he has changed the US role in the Middle East dispute from being that of a mediator to a supporter of Israel's intention to impose a settlement on the Palestinians, and that Mr Bush may be hoping the move will help him to win more Jewish campaign donations and votes in his bid for re-election later this year.