ISLAMABAD (Reuters) ― The United States and Pakistan are expected to agree soon on the reopening of land routes crucial to supplying NATO troops in Afghanistan, a Pakistani official said on Monday, a move that could ease a seven-month crisis in the two countries’ ties.

A senior Pakistani security official told Reuters a deal could be announced soon, potentially ending the long stalemate following a U.S. air attack last November that killed 24 Pakistani soldiers along the border with Afghanistan.

Senior Pakistani government and defense officials are due to meet to discuss the supply routes on Tuesday, a day after U.S. Deputy Secretary of State Thomas Nides headed back to Washington following talks with Pakistani officials.

“Things are looking very optimistic,” another Pakistani government official said, also speaking on condition of anonymity.

U.S. embassy officials declined to say if a deal was imminent.

While U.S. diplomats say they have made headway in recent talks, the two sides have appeared to have been on the brink of a deal before.

U.S. Secretary of State Hillary Clinton discussed the routes, which have become a major headache for NATO nations as they seek to keep troops equipped in Afghanistan, with new Pakistani Prime Minister Raja Pervez Ashraf when she called him over the weekend, the State Department said.

NATO nations, grappling with severe fiscal pressures at home, are anxious to reach an agreement, in part because shipping supplies into land-locked Afghanistan from the north costs 2 1/2 times as much as through Pakistan.

Pakistani media reported that Gen. John Allen, commander of NATO forces in Afghanistan, visited Islamabad on Monday for the second time in less than a week, but U.S. and Pakistani officials could not immediately confirm this.

Access to Afghanistan through Pakistan will become even more important as NATO commanders prepare to withdraw most of the 128,000 NATO soldiers in Afghanistan ― and the equipment they have accumulated since 2001 ― by the end of 2014.

But negotiations between U.S. and Pakistani officials in Islamabad have dragged on as Pakistan has insisted that the United States apologize for the air attack, which NATO described as an unfortunate accident.

The U.S. administration, seeking to shield President Barack Obama from Republican criticism months before a presidential election he hopes will hand him a second term, has refused such demands for months.

The details of the expected agreement remain unclear.

Islamabad has also sought a dramatic increase in the amount NATO nations pay to ship supplies into Afghanistan ― by some reports requesting a twenty-fold increase ― and payment of arrears in U.S. military support provided to Pakistan.

The November border incident marked a low point for U.S.-Pakistani relations, which have been plagued by mutual recriminations and mistrust since early 2011, when a CIA contractor was jailed in Pakistan.

Pakistani military leaders faced rare public criticism last year after the U.S. special forces raid ― carried out without Pakistani knowledge ― that killed al-Qaida leader Osama bin Laden deep inside the South Asian country.

Many officials in the Obama administration have been keen to reach a resolution as patience wears thin in the U.S. Congress, which sets assistance to Pakistan.

Last month U.S. Defense Secretary Leon Panetta said the United States should examine setting conditions to aid for Pakistan but not cutting it off.