A NATO airstrike hit two Afghan military checkpoints on Monday in a restive province east of the capital, Kabul, killing seven Afghan troops in what an Afghan official described as an accident due to bad coordination. The Afghan president, Ashraf Ghani, expressed his “profound sorrow” over the tragedy and ordered an investigation into the killings. The incident happened as coalition helicopters were flying over an area in Logar province where clashes were underway between Afghan troops and Taliban fighters, the Afghan Ministry of Defense said. Insurgents fired toward the helicopters, prompting a response that destroyed one army checkpoint, the ministry statement added. An unspecified number of the army members were “killed and wounded,” the ministry said, adding that the incident was under investigation.