Prime Minister Benjamin Netanyahu asserted Israel's sovereign right to defend itself at his meeting with US President Barack Obama on Monday.
Netanyahu made clear that Israel would be the "master of its fate" in deciding how to deal with Iran, which has called for the destruction of the Jewish state.
"It must have the ability to defend itself, by itself, against any threat," Netanyahu added.
Obama, seeking to head off an Israeli strike on Iran's nuclear program, sought to assure Netanyahu that Washington "has Israel's back."
"The bond between our two countries is unbreakable," Obama said at the start of an Oval Office meeting between the two leaders.
At the same time, Obama refused to commit to decisive action should Iran continue to buck sanctions and insisted his diplomatic track would prove effective.
The schism over Obama's dogged insistence on a sanctions-only approach to Iran has led to significant tension between Jerusalem and Washington.
Analysts say Netanyahu's decision to stress Israel's right to unilateral action in its own defense is a likely a stark warning for Obama, whom Israeli leaders see as indecisive.
US military officials have expressed concern that Israeli officials will not warn them ahead of a potential strike on Iran.
Israel's likely reason for cutting Washington out of the loop were recently laid bare by Sen. John McCain, who has charged Obama's administrations with deliberate leaks undermining Israel in its face off with Iran.
“The prime minister has every reason to be upset,” McCain said last week. “I can understand why relations are in very bad shape right now.”
They have also taken the unprecedented step of siding with Iran in accusing Israel of supporting the People's Mujahadeen of Iran in an assassination campaign targeting Iranian nuclear scientists.