NEW YORK — At the White House, President Bush welcomed the leaders of Pakistan and Afghanistan this week. Along their borders, safe havens for anti-U.S. militants, their troops exchanged fire, deepening a foreign policy challenge for the next American president.
These troubles are among the overseas entanglements that Bush’s successor — John McCain or Barack Obama — will inherit. It’s a crowded list: wars in Iraq and Afghanistan; inconclusive diplomatic efforts over Iran; North Korea’s nuclear programs; a faltering Middle East peace process.
Nuclear-armed Pakistan is struggling through internal political chaos. Questions have arisen about Islamist infiltration of its security services. A resurgent Taliban and al-Qaida have settled in along the border with Afghanistan. Combine all that with the long-standing tensions with archrival and neighbor India, and it is a combustible cocktail.
Just in the past week, Pakistan has seen one of the deadliest extremist attacks in its history — the truck bombing of the Marriott Hotel in Islamabad — and its military has exchanged ground fire with U.S. and Afghan troops near the border after shooting near American choppers.
Pakistan has come under intense U.S. pressure to do more against al-Qaida and Taliban insurgents in the country’s largely ungoverned tribal areas near the border with Afghanistan.
In response to allegations of Pakistani intelligence complicity in the bombing of the Indian Embassy in Kabul, Afghanistan this year, Bush expanded the authority of U.S. troops in Afghanistan to cross the border in pursuit of extremists — without Pakistani consent.
Pakistan loudly protested such incursions as violations of its sovereignty.
On Tuesday, Bush acknowledged tensions when he met Pakistan’s new president, Asif Ali Zardari, in New York. ‘‘Your words have been very strong about Pakistan’s sovereign right and sovereign duty to protect your country, and the United States wants to help,’’ he said.
Yet only two days later, Pakistani troops fired either warning shots or flares at two U.S. helicopters near the border, prompting a five-minute exchange of bullets below between ground forces and U.S. demands for explanations. There were no injuries or damage.
On Friday, as Bush met with Afghan President Hamid Karzai, America’s top military officer, Adm. Mike Mullen, acknowledged there was ‘‘hair-trigger tension we are all feeling.’’ He appealed for calm and teamwork.
Pakistan’s prime minister insisted on Saturday that his country is supportive of military action against extremists. Authorities said an offensive in Pakistan’s northwestern tribal area killed 16 suspected militants and that 35 had been captured near the region’s main city.
Yet Pakistan’s commitment to the fight and ability to do the job are being questioned, not least by one of the two men hoping to succeed Bush.
In the first presidential debate Friday, Democrat Barack Obama complained that Pakistan has failed to take strong enough action against terrorists despite the billions of dollars from the U.S. after Sept. 11, 2001.
‘‘They have not done what needs to be done to get rid of those safe havens,’’ Obama said. ‘‘If the United States has al-Qaida, bin Laden, top-level lieutenants in our sights, and Pakistan is unable or unwilling to act, then we should take them out.’’
Republican John McCain opted for a less aggressive public stance, questioning Obama’s threat to take matters into U.S. hands.
‘‘You don’t do that,’’ he said. ‘‘You don’t say that out loud. If you have to do things, you have to do things, and you work with the Pakistani government.’’
‘‘We’ve got to get the support of the people of Pakistan,’’ McCain said, referring mainly to those who live in the tribal areas. ‘‘And it’s going to be tough. But we have to get the cooperation of the people in those areas.’’