President Trump suggested in a visit to the Pentagon Thursday that he might hold off on sending more troops to Afghanistan, despite a recent order that he signed authorizing the Pentagon to add more forces.

Asked if he would send more troops to Afghanistan, where the Taliban have made significant gains in recent months, Trump replied: "We'll see. And we're doing very well against ISIS. ISIS is falling fast."

The fight against the Islamic State in Afghanistan is only a tiny piece of the broader battle in the country to stabilize Afghanistan's faltering central government and slow the Taliban's battlefield momentum.

Trump gave Defense Secretary Jim Mattis the authority more than a month ago to send as many as 3,900 additional troops to Afghanistan on top of the 8,500 currently there. Most of those forces would be used to bolster the Afghan Army in its fight against the Taliban, rather than battle the relatively small Islamic State force in the country.

But Mattis has yet to send those additional forces and some U.S. officials have speculated that either he or the White House could be having second thoughts.

"He's clearly being cautious about cashing that check," said a former U.S. official who has participated in the administration debate. "Mattis is either not persuaded that there's a strategic rationale for the troops or he's not persuaded that the decision will ultimately fly with the president — or both."

Trump's remarks at the Pentagon, where he met with senior commanders who gave him a briefing on the status of U.S. forces globally, is likely to add to the uncertainty surrounding the possible deployment of U.S. forces.

On Wednesday, Trump presided over a rare meeting of his full national security team Wednesday in the White House that focused on Afghanistan, Pakistan and the prospects for peace talks with the Taliban.

Trump has said little about America's longest war since taking office in January, but the debate over how to stabilize the country and reverse the Taliban's momentum has divided top officials in the Pentagon, the State Department and the White House in recent weeks.

The meeting Wednesday was designed to tee up final decisions for the president in what has been a long and difficult policy review, said current and former U.S. officials.

The meeting that Trump led in the White House did not focus on the size of the American force in Afghanistan but looked at America's broader approach to the region and its strategy regarding Pakistan, which has provided a haven for the Taliban.

National security adviser H.R. McMaster and U.S. commanders in Afghanistan have pressed for a more punitive approach to Pakistan aimed at forcing it to cut ties to the Afghan Taliban.

But such an approach has been met with skepticism by senior officials in the Pentagon and the State Department, who said that Pakistan is unlikely to change its behavior and that efforts to pressure Islamabad would likely lead to greater instability in the region.

Top U.S. officials have also been divided over whether to seek peace negotiations with the Taliban now or wait until the new U.S. strategy has begun to shift the momentum on the battlefield. "The McMaster view is that you should not negotiate with the Taliban while they are still ascendant," said the former U.S. official.

But the current U.S.-Afghan war strategy is built around a four-year plan to push back the Taliban that is not likely to yield significant results until its later stages, U.S. officials said.

Earlier this week, Trump met over lunch with service members who had fought in Afghanistan and suggested that his patience with the war might be running out.

"It's our longest war. We've been there for many years," Trump told reporters before the lunch. "We've been there for now close to 17 years, and I want to find out why we've been there for 17 years, how it's going, and what we should do in terms of additional ideas."

One challenge for Trump is that there are not a lot of new options available to him that do not come with a big price tag. In recent months, Trump has loosened the rules governing American airstrikes, allowing U.S. forces to boost the air campaign against the Taliban to levels not seen since 2012, when the United States had 100,000 troops in the country.

"I'm skeptical that the strategy can be dramatically improved," said Michael O'Hanlon, a senior fellow at the Brookings Institution. "You can try to be tougher on Pakistan. You can try to make clear that we are there for a long-term commitment. But I don't expect a dramatic metamorphosis of this mission."