KABUL, Afghanistan — Two gunmen wearing Afghan army uniforms killed a U.S. soldier and wounded two others Tuesday, just hours after Afghanistan's defense minister stepped down following a weekend no-confidence vote in parliament.
The exit of Defense Minister Abdul Rahim Wardak leaves a vacancy at the helm of the ministry that has overseen rapid expansion of the nation's army. Afghan soldiers are increasingly taking their positions on the front lines of the war as foreign combat troops withdraw.
NATO's goal is to turn over security responsibility to local forces by the end of 2014.
Mr. Wardak's resignation comes at the peak of the summer fighting season. Violence on Tuesday hit eastern and southern Afghanistan, where militants have their deepest roots.
The two gunmen wearing Afghan army uniforms fired on NATO troops at a base in Paktia province of eastern Afghanistan, killing a soldier, according to the U.S.-led coalition and Afghan officials.
The Taliban took responsibility for the shooting in the latest in a rising number of so-called "green-on-blue" attacks in which Afghan security forces, or insurgents disguised in their uniforms, kill their U.S. or NATO partners.
The international military coalition did not disclose the nationality of the service member killed, but a U.S. official said he was American.
A second American official said two U.S. service members were wounded.
The officials spoke on the condition of anonymity because they were not authorized to disclose the information to reporters.
So far this year, 27 coalition troops have been killed in 20 such attacks, according to an Associated Press tally. That compares with 11 fatal attacks and 20 deaths the previous year. In 2007 and 2008 there was a combined total of four attacks and four deaths.
Overall this year, 272 U.S. and NATO troops have died in Afghanistan.
The Taliban also took responsibility for Tuesday's midmorning blast at a NATO base in Logar province, southeast of Kabul.
A suicide attacker, who placed explosives under a load of gravel, drove a pickup truck into a gate of the base near Logar's capital of Pul-i-Alam, provincial police chief Ghulam Sakhi Roogh Lawanay said. At least 11 Afghan civilians were wounded, he said.
Earlier, a remote-controlled roadside bomb struck a bus heading northwest of Kabul, killing at least nine passengers, police said. The militant who set off the device was captured by local villagers in Paghman district of Kabul province.
The latest shooting of a NATO soldier was a setback for the Afghan army just as the Defense Ministry lost its leader.
Lawmakers passed no-confidence votes Saturday against Mr. Wardak and Interior Minister Bismullah Khan Mohammadi, faulting them for what they said was the government's weak response to cross-border attacks that Afghans blame on the Pakistani military.
"As an Afghan citizen, I believe in democracy, and I respect [the parliament's] decision," Mr. Wardak said, explaining why he was stepping down instead of continuing as a caretaker minister, despite President Hamid Karzai's offer.
Mr. Wardak served in the Afghan government through more than four decades of national turmoil. He oversaw growth of the army from around 50,000 to more than 195,000, but it remains beset by corruption and unprofessionalism.