CONFLICT ENTERS FOURTH DAY: Israel and Iran have begun a new round of attacks, as the conflict between the two heavily armed rivals enters its fourth day.

Israel and Iran both have little incentive to stop and no obvious route to outright victory. Much depends on President Trump.

President Donald Trump is desperate not to fight a war with Iran. But can he really avoid it? Compelling national security arguments and domestic political considerations mean it makes sense to stop short of direct US offensive operations in the long-dreaded conflict that Israel describes as a matter of preserving its own existence.

"The full strength and might of the U.S. Armed Forces will come down on you at levels never seen before," Trump warned.

A Democratic senator introduced legislation on Monday to prevent U.S. President Donald Trump from using military force against Iran without Congress's authorization, as an escalating battle between Israel and Iran raised fears of broader conflict.

The "America First" president praised his foreign policy record on Sunday while urging a deal between Iran and Israel amid escalating strikes.

Israel’s attack on Iran was long in the making – the result of years of meticulous planning by Israel and days of high-stakes talks between Tel Aviv and Washington, officials told CNN.

President Trump is trapped between the “America First” isolationists and others in his party who are cheering on Israel’s strikes against Iran.