His latest comments come as that deal, signed in February, endangered by a sharp spike in Taliban attacks on Afghan government forces, faces a precarious path forward. The militant group and Afghan government have agreed to a 10-day truce to reduce violence and to the release of hundreds of prisoners, laying the groundwork for peace negotiations nearly three months after they were scheduled.
"We are acting as a police force, not the fighting force that we are, in Afghanistan," the president tweeted on Wednesday. "After 19 years, it is time for them to police their own Country. Bring our soldiers back home but closely watch what is going on and strike with a thunder like never before, if necessary!"
The peace deal between the U.S. and the Taliban called for a reduction in the number of American forces from about 13,000 to 8,600 by mid-July. At the height of the nearly two-decade conflict, there were approximately 100,000 troops in the country.
A U.S. official told ABC News on Wednesday that the number of U.S. service members currently in Afghanistan is between 8,600 and 10,000, despite the president telling reporters on Tuesday that "we are down to 7,000-some-odd soldiers right now." A second official said that the U.S. draw down is "well ahead of schedule" and "close to reaching" that 8,600 number.
The U.S. is set to withdraw all forces in 14 months if the Taliban also uphold their commitments in the agreement -- to sit with an Afghan national delegation for peace negotiations and to break ties with terror groups like al-Qaida.
"Any reductions under (8,600) will be conditions-based, after the U.S. government assesses the security environment and the Taliban's compliance with the agreement, and in coordination with our NATO allies and partners," said chief Pentagon spokesperson Jonathan Hoffman during a briefing on Tuesday.
But there is concern that Trump, who has pledged to "end America's endless wars" in Afghanistan and Iraq, will push for a quicker withdrawal or one that disregards those conditions on the ground.
His public statements on Afghanistan followed a New York Times report that senior military officials were preparing to brief Trump this week about options for pulling troops out of Afghanistan, including an option for a full withdrawal before the U.S. presidential election in November -- though the officials would not advocate for that option, the Times said.
Asked about a November target date for a withdrawal, Trump said on Tuesday, "No, I have no target but as soon as reasonable."
The aftermath of the U.S.-Taliban agreement got off to a rocky start with an escalation in violence by the Taliban against Afghan forces, domestic political squabbles, and an inability to agree on a prisoner exchanges. However, there has been positive momentum in the last couple weeks as the the Taliban and Afghan government work toward face-to-face peace talks of their own.
Over the weekend, the Taliban announced a three-day ceasefire during the Eid holiday, and the Afghan government agreed to release 2,000 Taliban fighters it held in custody. Earlier this month, Afghan government leadership also committed to a power-sharing agreement.
Eight American service members have died and 11 have been wounded serving in Afghanistan this year, according to Defense Department data.