Militants crossed into Pakistan from Afghanistan and killed 13 Pakistani troops, beheading seven of them, the Pakistani military charged Monday.

A bomb tore through a bus carrying government employees and other civilians in northwestern Pakistan on Friday, killing 18 people in an attack that served as a reminder of the continued militant threat despite a significant drop in violence over the past year, officials said.

U.S. Defense Secretary Leon Panetta on Thursday pressured Pakistan to do more to root out the al Qaeda-linked Haqqani terrorist network from its territory, saying that U.S. officials are "reaching the limits of our patience."

Pakistani officials on Monday condemned the U.S. for carrying out its first drone strike in the country since parliament demanded they end two weeks ago, but qualified that it should be seen in light of the presence of Islamist militants on Pakistani soil.

Pakistan successfully launched an upgraded ballistic missile capable of carrying a nuclear warhead Wednesday, days after its neighbor and archenemy India conducted its own missile test, the Pakistani military said.

The top commander of coalition forces in Afghanistan's Helmand province said Monday that Pakistani troops have been no help in targeting insurgents hiding in safe havens in Pakistan.

One of Pakistan's most notorious extremists mocked the United States during a defiant media conference close to the country's military headquarters Wednesday, a day after the U.S. slapped a $10 million bounty on him.

Pakistan's leading militants have called on fighters to honor an agreement not to attack the Pakistani military in the most important sanctuary for the Taliban and al Qaeda along the Afghan border.

Pakistan's government faced a constitutional threat Monday from the Supreme Court, which began contempt proceedings against the prime minister for failing to reopen a corruption investigation against the president.