Trump at Camp David on Friday for Afghanistan talks

US President Donald Trump will meet Friday with his national security team at Camp David, as he mulls whether or not to send more American troops to war-ravaged Afghanistan.

The administration is split over what stance to adopt on the longest-running war in US history.

Possible plans include sending thousands more troops into the nearly 16-year conflict, or taking the opposite tack and pulling out, leaving private military contractors to help the Afghans oversee the fragile security situation.

"The president along with the vice president will meet with the national security team on Friday at Camp David to discuss the South Asia strategy," the White House said.

Trump's generals have called the Afghan conflict a "stalemate" and even after years of intensive help from the US and other NATO nations, Afghanistan's security forces are still struggling to hold back an emboldened Taliban.

In an early move to address the situation, Trump gave his Pentagon chief, former general Jim Mattis, broad powers to set troop numbers.

But several months later, the level remains stuck at about 8,400 US and about 5,000 NATO troops, mainly serving in a training and advisory capacity.

Mattis wants to wait until the White House has come up with a coherent strategy for not just Afghanistan but the broader region, notably Pakistan and how it deals with terror groups, before he commits to adjustments.

But reports have suggested that other Trump advisers, including his influential strategy chief Steve Bannon, favor cutting American losses by pulling out or sending private military contractors to replace troops.