KABUL : The United States is already reducing the size of its troop force in Afghanistan despite the lack of a peace deal with the Taliban, at a time when President Trump has expressed reluctance to remain engaged in costly wars abroad. In a news conference on Monday, the top American commander in Afghanistan, Gen. Austin S. Miller, confirmed that the size of the American force in the country had already quietly dropped by 2,000 over the last year, down to between roughly 13,000 and 12,000. Other American and Afghan officials, speaking on condition of anonymity to discuss details of the plan, said that the eventual force size could drop to as low as 8,600 — roughly the size of an initial reduction envisioned in a draft agreement with the Taliban before Trump halted peace talks last month. Rather than a formal withdrawal order, they are reducing the force through a gradual process of not replacing troops as they cycle out. A senior Afghan official said the Afghan government had signed off on the reduction. Officials would not discuss other details of the drawdown, including any specific timeline for it. The confirmation came during a visit to Afghanistan by Defense Secretary Mark T. Esper, and after months of debate within the Trump administration on meeting the president’s goal of stopping what he has recently called “endless wars.” Earlier in his visit, Esper seemed to allude to some potential reduction in American forces, saying that drawing down to 8,600 troops would not affect important counterterrorism operations in Afghanistan. As Trump grew frustrated over the past year, diplomats tried to package an American troop reduction as a bargaining chip in peace talks with the Taliban, hoping to get some concessions from the insurgent group, which has long demanded a complete American troop withdrawal. The decision to reduce American troops even before a deal with the Taliban means the United States is weakening its hand in future negotiations with the insurgents. And it is likely to mean a significant shift away from the United States military’s longstanding mission of training the Afghan military as American officials concentrate on counterterrorism operations, officials said. Reducing the number of troops ahead of a complete departure from the country was always the most important American bargaining chip in any negotiations with the Taliban to end the long war. But from the start, Trump made it abundantly clear that he wanted out of Afghanistan. At one stage halfway through the yearlong negotiations, Trump stumbled during a Fox interview, incorrectly saying that the number of American troops in Afghanistan was 9,000 and not the roughly 14,000 it was listed at. Many, including some Taliban officials taking part in the talks in Qatar, read that as confirmation that the American decision to draw down had already been made whether the Taliban offered concessions or not. Much of the initial effort by American negotiators was trying to persuade the Taliban that the United States was truly committed to Afghanistan, while signaling that the insurgents should not try to wait out the Americans. U.S. Defense Secretary Esper said on Monday that while the United States did not have a commitment to defend Syrian Kurdish fighters against Turkey, it does have a “longstanding commitment” to Afghan security forces. “We had no obligation, if you will, to defend the Kurds against a longstanding NATO ally,” Esper told reporters in Kabul. “We have a longstanding commitment to our Afghan partners, we’ve invested billions upon billions of dollars, both the Afghan people and the American people have sacrificed treasure and the lives of their soldiers,” he told a news conference. US President Trump’s abrupt decision earlier this month to withdraw all 1,000 American troops from northern Syria has been criticized in Washington and elsewhere as a betrayal of loyal Kurdish allies who had fought for years alongside U.S. forces against Islamic State. Esper, standing next to his Afghan counterpart, said the Syria withdrawal should not be compared to Afghanistan, where the situation was “very, very different.” U.S. troops were removed from northeast Syria because they were potentially at risk from a Turkish incursion into the region, he said.