Israeli warplanes struck and killed three Iranian commanders, Israel’s defense ministry said Saturday, including the head of the force that supports the Palestinian group Hamas and other proxy militias around the Middle East.

The reported killing of the commanders expanded Israel’s tally of assassinated Iranian officials in the nine days of war between the two countries. Israel identified the commander of the force that coordinates with proxy militias as Mohammed Said Izadi, and said he was killed in an assault on the holy city of Qum.

The new attacks came amid fears that the war could expand with the involvement of the United States, a prospect that President Trump has kept vague, leaving the world guessing his intentions.

Mr. Trump was scheduled to travel late Saturday afternoon from his golf club in Bedminster, N.J., to Washington, where he was to meet with his national security team in the evening and then again on Sunday. The president typically spends both weekend days out of town at one of his properties.

Before Mr. Trump’s return to the White House, flight tracker data suggested multiple B-2 military aircraft had taken off from a Midwestern military base. Defense analysts took note of flight movements amid the president’s deliberations about whether to join Israel’s efforts to destroy Iran’s nuclear sites. Only Washington possesses the 30,000-pound bomb many consider essential to an air assault on Fordo, a deeply buried nuclear complex — and the aircraft, the B-2, capable of delivering the munition.

The movement of the B-2s, however, did not mean a final decision had been made about whether to strike. It is not unusual to shift military assets into position to provide options to the president and military commanders even if they are not ultimately deployed.