Tehran in response has warned that it is prepared to hit US bases in the region if Trump pulls the trigger:

Iran has prepared missiles and other military equipment for strikes on U.S. bases in the Middle East should the United States join Israel's war against the country, according to American officials who have reviewed intelligence reports.

The United States has sent about three dozen refueling aircraft to Europe that could be used to assist fighter jets protecting American bases or that would be used to extend the range of bombers involved in any possible strike on Iranian nuclear facilities.

Fears of a wider war are growing among American officials as Israel presses the White House to intervene in its conflict with Iran. If the United States joins the Israeli campaign and strikes Fordo, a key Iranian nuclear facility, the Iranian-backed Houthi militia will almost certainly resume striking ships in the Red Sea, the officials said. They added that pro-Iranian militias in Iraq and Syria would probably try to attack U.S. bases there.

And more: "Other officials said that in the event of an attack, Iran could begin to mine the Strait of Hormuz, a tactic meant to pin American warships in the Persian Gulf," NYT writes.

Meanwhile, the exiled US-backed Iranian monarchy is urgently calling for Iranians to rise up in the streets against the Ayatollah, in a massive development. Reza Pahlavi is issuing these statements from US soil, where the family has long resided...

Trump's national security council meeting in the WH Situation Room has ended. Will tonight bring US warplanes and pilots directly into the conflict - and American troops at regional bases into harm's way?

US strikes on Iranian nuclear facilities are on the table, two senior White House officials tell Fox News

Axios reviews of the latest:

The White House has discussed the idea of meeting directly with the Iranians this week, but Trump said that would "depend what happens when I get back" to Washington.

Two Israeli officials told Axios that Prime Minister Benjamin Netanyahu and the Israeli defense establishment continue to believe the Trump is likely to enter the war in the coming days to bomb Iran's underground enrichment facility.

So far the U.S. has helped Israel defend itself from incoming missiles, but declined to take part in offensive operations.