Updated

The top U.S. commander in Afghanistan held talks with Pakistan's army chief Saturday aimed at improving border coordination, almost six months after American airstrikes accidentally killed 24 Pakistani soldiers along the frontier.

Islamabad retaliated for the deaths in November by closing its border crossings to supplies meant for NATO troops in Afghanistan. The border remains closed despite U.S. pressure to reopen the route, which has long been one of the main ways to get goods and equipment to coalition forces in landlocked Afghanistan.

Pakistan's parliament has demanded that the Washington apologize for last year's attack and stop drone strikes targeting militants in the country's tribal region along the Afghan border. Although Pakistani lawmakers have not explicitly linked these issues to reopening the supply route, the matters have complicated the discussions.

The U.S. has expressed its condolences for the deaths of the Pakistani soldiers at two Afghan border posts, but has stopped short of a full apology, likely because of domestic political considerations. The Obama administration may fear criticism from members of Congress and Republican presidential contender Mitt Romney, given anger toward Pakistan for allegedly coddling militants attacking U.S. troops in Afghanistan.

U.S. officials have made clear in private that they have no intention of stopping covert CIA drone strikes in Pakistan, and several attacks have occurred since parliament demanded they stop. The strikes are immensely unpopular in Pakistan because many people believe they mostly kill civilians, allegations disputed by the U.S. and independent research.

The issue is complicated by the fact that Pakistan is widely believed to have supported some of the strikes in the past, although that cooperation has come under strain as the relationship between the Washington and Islamabad has deteriorated.

Despite the disagreements between the two countries, Saturday's talks between U.S. Gen. John Allen and Pakistani army chief Gen. Ashfaq Parvez Kayani indicates some level of progress in the relationship. The meeting, which the Pakistani army announced in a written statement, followed several other discussions between senior U.S. and Pakistani officials in recent weeks.

There is incentive on both sides to resolve the impasse over the NATO supply route. The U.S. has had to spend considerably more money over the past few months shipping supplies to Afghanistan through the more expensive northern route that runs through Central Asia. The route through Pakistan will become even more important as the U.S. begins to pull out equipment as it withdraws most of its combat troops from Afghanistan by the end of 2014.

Islamabad is eager to free up more than a billion dollars in U.S. military aid that has been frozen for the past year and would likely only be released once the supply route is reopened. Another potential carrot could be an invitation to the NATO summit in Chicago on May 20-21, which will largely focus on the Afghan war.

A pair of high-level meetings are expected to take place in Pakistan this week to discuss reopening the NATO supply route. They include one by the Cabinet and another by the defense committee of the Cabinet, which includes the head of the Pakistan army and its powerful intelligence arm, the ISI.

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Associated Press writer Zarar Khan contributed to this report.