US President Donald Trump is holding off on a final decision over a possible military strike on Iran, after advisers warned that even a major assault is unlikely to collapse the government and could ignite a broader regional conflict.

US officials said Trump has been advised that a massive strike on Iran would probably not cause the regime to fall. Instead, such an operation could draw the United States into a wider war across the Middle East, as reported by The Wall Street Journal.

Officials and regional partners also warned that smaller, limited strikes might boost protesters’ morale but would not stop Tehran’s crackdown. The assessments were shared with the White House as Trump considers his options.

Military preparations underway

Although Trump has not decided on the scale of any action, officials said he asked the Pentagon to ensure military assets are in place in case he orders a major attack. Advisers told him the US would need significantly more firepower in the region to both strike Iran and defend American forces and allies, including Israel.

Also Read: Netanyahu urges Trump to delay US strike on Iran

NBC News earlier reported that Trump’s advisers could not guarantee Iran’s leadership would quickly collapse after a US strike.

White House issues warning to Tehran

White House press secretary Karoline Leavitt said on Thursday that Washington had warned Iran of “grave consequences” if killings of protesters continued. She added that only Trump and a very small group of advisers know what decision he will ultimately make.

Leavitt also said the US learned Wednesday of Iranian plans to execute 800 people, which did not occur. She did not disclose how the information was obtained.

Leavitt confirmed Trump recently spoke with Israeli Prime Minister Benjamin Netanyahu, though she declined to share details. US officials said Israel raised concerns about a potential American strike and its regional fallout.

Intelligence briefings, Congressional reactions

CIA Director John Ratcliffe showed Trump covertly obtained videos of dead Iranian protesters earlier this week, as the president met senior advisers to review Iran options.

Republican Senator Lindsey Graham said the size of a possible operation remains under debate. He said he favors a larger strike and hopes “the regime’s days are numbered.”

Also Read: Trump questions Pahlavi's ability to lead Iran, support in country

Iranian officials have contacted Turkey, Qatar, United Arab Emirates and Oman, warning that Iran would strike US bases if attacked.

A diplomat said the most likely target would be the large US military base in Qatar, which Iran struck last June after US attacks on Iranian nuclear sites. As a precaution, the US has moved some troops off the base, with some housed in hotels.

Regional allies push for restraint

US partners, including Turkey, Qatar and Saudi Arabia, have urged Trump not to attack Iran. Turkish Foreign Minister Hakan Fidan said he has been calling and meeting regional leaders, including Iranian officials, to prevent escalation.

“We do not want an intervention here,” Fidan told reporters in Istanbul.

Despite diplomatic efforts, US officials said Trump is expected to order the aircraft carrier USS Abraham Lincoln to sail from the South China Sea to the Middle East. Once the deployment begins, the voyage is expected to take about a week.

Protests, red lines, Trump’s shifting tone

The internal debates highlight the difficulty of enforcing Trump’s red line that Iran must not kill protesters en masse. Iran’s crackdown has killed thousands and forced demonstrators off the streets in some cities, leaving Trump with options that stop short of toppling the regime or fully backing the uprising.

Trump said Tuesday that “help is on its way,” urging protesters to keep up pressure. A day later, he said Iran had indicated it would stop killings and executions, raising the possibility that strikes could be avoided if restraint continues.

Also Read: Iran warns US of retaliation over strikes, US withdraws personnel

On Thursday, Trump welcomed reports that executions would not go ahead, posting online: “Good news. Hopefully, it will continue!” US and Middle Eastern officials said the president may be stalling as military assets move closer to the region.

One Qatari official said the US could need five to seven days to fully prepare a large-scale offensive.