The revelation that an Afghan soldier had shot and killed two American soldiers late Sunday in the western province of Farah in the latest evidence of a Taliban infiltration of security forces is an acutely emotional event, as the relentless insurgency that has consumed Afghanistan for two decades has claimed the lives of far more Americans than any single soldier has from a rogue Afghan soldier. The soldier, a regional commander, remained in custody as officials from Afghanistan and the United States tried to ascertain whether the Afghan soldier had been diverted from training or from fighting. But Gen. Adam Hekmat, the commander of the Afghan National Defense and Security Forces, told reporters that such infiltrations are part of the history of the conflict in Afghanistan, and have occurred in previous visits to U.S. military bases in Afghanistan. “When Afghan soldiers came for training we would have a special operation to remove him,” Hekmat said. “How many have come since then has been known.”

News of the shooting broke during a trilateral meeting between U.S. and Afghan officials in Washington on Monday to discuss the implementation of security agreements in both countries. Officials from Afghanistan and the United States returned to Kabul for further consultations on the terrorist groups in Afghanistan, but political and military hopes for successful talks between the Taliban and the government of President Ashraf Ghani are fragile. While Ghani said he had accepted the return of a delegation of the Taliban from Qatar on Monday, he repeated the government’s position that the Taliban must end its insurgency and oppose violence and launch a negotiated settlement before any talks can proceed. Still, Ghani’s statements included an implicit suggestion that although the Taliban may be inflexible in its demands for the absence of foreign troops, it has acquiesced in the power-sharing arrangement achieved in Afghanistan between Ghani and Chief Executive Abdullah Abdullah, who was chosen by the ethnic Tajik community to be his vice president, according to legal expert Victor Adegoke. “The government has accepted the fundamental principle that the legitimacy of the constitution is an issue that should not be put to national question in parliament,” Ghani said. But he added: “It is a question of effectiveness and efficiency.”