The Pentagon on Monday was to present the White House with possible new battle plans to defeat the Islamic State group, after President Donald Trump demanded top brass find additional ways to destroy the jihadists.

A pillar of Trump's campaign was to quicken the fight against IS, which despite losing thousands of fighters still controls parts of northern Syria and Iraq, and he berated the Barack Obama adminstration for taking too long to do so.

Trump had claimed to have a secret plan to defeat IS, but never disclosed what this might be. He repeatedly pledged to "bomb the hell" out of the jihadists and even threatened to kill family members of suspected IS fighters.

Shortly after taking office, the new president gave the Pentagon 30 days to come up with a comprehensive review of the fight against IS, which a US-led coalition has been bombing in Iraq and Syria since late summer 2014, while also using commandos to train and advise local forces.

The initial version of that review is now complete, and Defense Secretary Jim Mattis will present the findings to Trump's top national security advisors later Monday.

Though broad in scope, the options outlined in the classified review are preliminary and need to be further refined, Pentagon spokesman Navy Captain Jeff Davis said.

"It is about the rapid the defeat of ISIS," Davis said.

"We're going to continue to have a dialogue with our chain of command going forward and developing this plan."

The proposals will likely outline the possibility of sending more US troops to the Middle East and could see the Pentagon taking a more aggressive stance in other key areas.

"This is not about Syria and Iraq, it's about a trans-regional threat," General Joe Dunford, who is chairman of the Joint Chiefs of Staff, told a Washington audience last week.

"In this particular case we're talking about ISIS, but it's also Al-Qaeda and other groups that present a trans-regional threat."

Dunford stressed the importance of renewed military action coming alongside diplomatic and political efforts.

"All of us who have participated in these conflicts over the last 15 years realize that anything we do on the ground has to be in the context of political objectives or it's not going to be successful," Dunford said.

The review includes input from across the government, including its spy agencies, State Department and Department of Homeland Security.

- More US forces? -

Since the coalition effort to defeat IS began, the jihadists have lost much of the ground they once held, and tens of thousands have been killed.

In Iraq, they are clinging to the last parts of their former bastion Mosul as Iraqi security forces backed by Western air power push them from the city.

The fight is more complex in civil war-torn Syria, where Russia is conducting its own air campaign to prop up President Bashar al-Assad.

A key question is whether America will arm Syrian Kurdish forces to lead the fight to retake Raqa -- a move sure to infuriate ally Turkey, which considers the Kurdish fighters terrorists -- or whether the United States should send in more combat troops.

Currently, only about 500 US troops are in Syria, mostly special operations forces working behind the front lines to train local Kurdish and Syrian Arab fighters.

Because Obama was elected in 2008 on the promise of ending US conflicts in the Middle East, he was loath to put US forces in combat.

The anti-IS review is also a significant first test for the relationship between Trump and Mattis.

Trump has so far given the Pentagon chief broad leeway on shaping US military policy, even though the retired Marine Corps general has pushed back against much of Trump's more blustery rhetoric, including his professed support of torture and claim that America should seize Iraq's oil.