Pakistan ? A suicide bomber rammed an explosives-laden vehicle into a mess hall inside a high-security base used by a Pakistani counterterrorism force, killing at least 15 soldiers, officials said.

The militants’ ability to penetrate the elite force’s headquarters about 60 miles south of the capital was a severe blow to the army. It came hours after visiting U.S. Deputy Secretary of State John D. Negroponte met in Islamabad with President Gen. Pervez Musharraf, a key ally in Washington’s war on terrorism.

The army reported, meanwhile, that it had killed as many as 50 militants in a battle in the South Waziristan tribal region near the Afghan border.

The victims of the suicide attack belonged to the Karar commando group, which has participated in operations against Islamic militants in various parts of the country, according to two security officials who spoke on condition of anonymity because of the sensitive nature of their jobs.

They said the bomber struck while dozens of soldiers were eating.