Prime Minister Benjamin Netanyahu bluntly told Barack Obama that he would never compromise on Israel's security even as the US president sought to reassure him on Iran nuclear diplomacy and pressure him on Middle East peace talks.
In a White House meeting overshadowed by the Ukraine crisis on Monday, the two leaders avoided any direct clash but were unable to paper over differences on a pair of sensitive diplomatic drives that have stoked tensions between them.
Obama assured Netanyahu of his "absolute commitment" to preventing Iran from developing atomic weapons, despite the Israeli leader's deep scepticism over US-led efforts to reach a final international deal to curb Tehran's nuclear programme.
But, warning that time was running out, Obama also urged Netanyahu to make "tough decisions" to help salvage a faltering US-brokered peace process aimed at reaching a framework agreement with the Palestinians and extending talks beyond an April target date for an elusive final accord.
"The Israeli people expect me to stand strong against criticism and pressure," Netanyahu told Obama.
The two, who have had strained relations in the past, showed no outright tension as they sat side-by-side in the Oval Office. Both were cordial and businesslike. But their differences were clear, and when the talks ended after nearly three hours there was no immediate sign of progress.
Netanyahu arrived in Washington to a veiled warning from Obama that it would be harder to protect Israel against efforts to isolate it internationally if peace efforts failed.
The Israeli prime minister used their brief joint appearance to put the onus on the Palestinians to advance prospects for peace and also to vow to hold the line on what he sees as Israel's security imperative.
Obama was essentially given a history lesson covering the last 20 years of conflict with the Palestinians as well as what Israelis see as an existential threat from Iran.