US President Donald Trump was advised that a large-scale military strike against Iran would be unlikely to make the Islamic Republic's regime fall, and may have sparked a wider conflict, US officials told The Wall Street Journal on Thursday.

Trump, for now, would monitor how Tehran handles ongoing protest activity before deciding on the scope of any potential military action, the report noted.

The US military would need more firepower in the region in order to launch a large-scale military action, protect US forces mobilized in the region, and to protect regional allies, including Israel, if Iran were to retaliate against a strike, the advisers told Trump, according to the officials.

However, smaller military actions could boost morale among protesters nationwide, even if it ultimately did not change the regime's clampdown on activists, the officials told the outlet.

Trump, while not having made a final decision, has requested that US military assets be mobilized in preparation for a possible large-scale attack order, the officials said.

White House Press Secretary Karoline Leavitt speaks during a press briefing in the Brady Briefing Room of the White House in Washington, January 15, 2026.
White House Press Secretary Karoline Leavitt speaks during a press briefing in the Brady Briefing Room of the White House in Washington, January 15, 2026. (credit: MANDEL NGAN/AFP via GETTY IMAGES)

Trump and his team "have communicated to the Iranian regime that if the killing continues, there will be grave consequences,” White House press secretary Karoline Leavitt said on Thursday.

Leavitt: Only Trump knows what he will do in Iran

Only Trump knows what he is going to do, and a "very, very small team of advisors are read into his thinking," she added.

Trump is likely to order the USS Abraham Lincoln to reposition from the South China Sea to the Middle East, two US officials and one other person familiar with the move told WSJ. This journey would last approximately a week, they noted.

Meanwhile, Senator Lindsey Graham told reporters that he is supportive of a larger-scale strike, WSJ reported, adding that he hopes the Iranian regime's "days are numbered."