Across Europe on Thursday, Americans scrambled to make sense of conflicting messages from Washington about if and when they would be allowed to return to the United States.

They awoke to the news that President Trump had announced a 30-day suspension of most travel from Europe in a bid to stem the spread of the coronavirus.

“To keep new cases from entering our shores, we will be suspending all travel from Europe to the United States for the next 30 days,” Mr. Trump said. The travel restrictions would start at midnight Friday, he added.

[Read: Italy’s coronavirus victims face death alone, with funerals postponed.]

Alex Sarnow of San Diego was one of many Americans alerted by family members in the early morning. “My phone started buzzing and ringing off the hook at 3 a.m.,” said Mr. Sarnow, who was vacationing with his wife in Malta.