The president did not specify what actions he would take, and he has on other occasions abandoned threats to dramatically escalate the war with Iran.

© Al Drago for The New York Times

The United Arab Emirates, Iran’s most important regional trading partner, announced a total embargo on transactions with Tehran on Tuesday.

© Raghed Waked/Reuters

Iran has survived decades of sanctions. Faced with more, it is likely to escalate rather than surrender, analysts said.

© Arash Khamooshi/Polaris for The New York Times