The United States and Israel showed signs of seeking to defuse tensions on Sunday ahead of a speech in Washington by Israeli leader Benjamin Netanyahu when he will warn against a possible nuclear deal with Iran.

Policy differences over the negotiations with Iran remained firm, however, as Netanyahu set off for the United States to deliver the speech, which has imperiled ties between the two allies.

Israel fears that U.S. President Barack Obama's Iran diplomacy, with an end-of-March deadline for a framework accord, will allow its arch foe to develop atomic weapons —something Tehran denies seeking.