Senator Ron Johnson said he hoped President Trump was making empty threats, but most in the G.O.P. cheered his warning that Iran’s “whole civilization” would be wiped out.

G.O.P. lawmakers who have given the Trump administration wide latitude to wage war with no congressional input are growing frustrated as officials offer little detail about ground troops, cost or timeline.

In the first days of the U.S.-Israeli campaign against Iran, Mr. Trump pressed for a popular uprising against Tehran’s government.

President Trump’s war in Iran has raised some costs just as many Americans are starting to see savings from last year’s tax cuts.

JD Vance long championed opposition to conflicts abroad. With President Trump all-in on war with Iran, the vice president is staying loyal even as allies make his qualms known.