“There’s going to be a breaking point sooner or later,” one union official warned, with travelers at some airports being told to arrive three hours ahead of time.

The president is no stranger to staking out contradictory stands, part of what his aides say is his negotiating style. But on Iran, his shifting positions are colliding with the consequences of war.

While some European countries said they were discussing ways to help reopen the Strait of Hormuz, several rejected President Trump’s calls to send warships.