Updated 6:40 PM ET
(CBS/AP) WASHINGTON - The Obama administration said Tuesday that Pakistan was reopening its supply lines into Afghanistan, after the U.S. belatedly issued an apology for the November killing of 24 Pakistani troops in a NATO airstrike.
Secretary of State Hillary Rodham Clinton expressed her condolences for the deaths in a telephone conversation with Pakistani Foreign Minister Hina Rabbani Khar. The incident badly damaged already strained relations between the two countries and forced the U.S. and its allies to send supplies via costlier northern routes into Afghanistan.
"We are sorry for the losses suffered by the Pakistani military," Clinton said in a statement, recounting her discussion with Khar. "I offered our sincere condolences to the families of the Pakistani soldiers who lost their lives. Foreign Minister Khar and I acknowledged the mistakes that resulted in the loss of Pakistani military lives."
It is the first time any U.S. official has formally apologized for the deaths, a step hotly debated within the Obama administration and one demanded by Pakistan while its supply routes remained closed for seven months. It came as key Pakistani civilian and military leaders were meeting Tuesday evening in Islamabad to discuss whether to reopen NATO supply routes.
Some 7,000 truckloads of equipment bound for the U.S. military in Afghainstan have been stranded in Pakistan, reports CBS News correspondent David Martin. Now that the supply lines have been reopened, Pentagon officials estimate it will take about two months to clear that backlog which stretches some 900 miles from the border to the port of Karachi.
"I am pleased that Foreign Minister Khar has informed me that the ground supply lines into Afghanistan are opening," Clinton said. She said Pakistan won't charge any transit fee, the subject of an earlier negotiation, and that the reopening would help the U.S. draw down its war in Afghanistan "at a much lower cost."
The U.S. government has never paid any transit fees directly. Pakistan charges companies $250 per truck for transit and the U.S. accounts for those fees in its contracts with those companies, so it pays indirectly.
Those fees will not change, two U.S. officials said on condition of anonymity because they weren't authorized to speak publicly about the deal. The first trucks carrying NATO goods should move across the border on Wednesday, they said, but it could take days to ramp up supplies to pre-attack levels.
"This is a tangible demonstration of Pakistan's support for a secure, peaceful, and prosperous Afghanistan and our shared objectives in the region," Clinton said, calling the agreement "critically important to the men and women who are fighting terrorism and extremism in Afghanistan."
Defense Secretary Leon Panetta also welcomed Pakistan's decision.
"As I have made clear, we remain committed to improving our partnership with Pakistan and to working closely together as our two nations confront common security challenges in the region," he said.
The dispute over the supply lines had plunged relations between Pakistan and the U.S. to new lows, coming after a CIA contractor killed two Pakistanis and the unilateral U.S. raid on Osama bin Laden's Pakistani compound. Tensions are compounded by the U.S. suspicion that Pakistan supports the Taliban, making the Afghanistan war unwinnable.
The Taliban and other militant groups - particularly the Haqqani network, which is also suspected of links to Pakistani security forces - continue to represent a security threat to the convoys.
Highlighting that threat, a Pakistani security official told CBS News' Farhan Bokhari on Tuesday that there was, "concern that these attacks will resume in the not too distant future" following the intercept of recent Taliban communications discussing plans to launch attacks on the trucks.
Domestic concerns on both sides made an agreement more difficult.
Pakistan's government, worried about the inevitable political backlash from reopening the route, given the high level of anti-American sentiment in the country, held out for a higher transit tax and a clear apology for the November incident near the Afghan border.
The Obama administration, in the midst of an election year, expressed regret but dug in its heels over the word "sorry," apparently fearful it would open the president to criticism from Republicans angry over Pakistan's links with militants fighting in Afghanistan.
Pakistan had been demanding a complete apology, but Clinton's "sorry" apologized only for the 24 dead and not for the incident itself, which a U.S. investigation concluded was caused by mistakes on both sides.
U.S. officials believe the Pakistanis accepted that more limited apology because the closure of the supply routes was hurting Pakistan financially at least as much as the U.S.
With the supply lines closed, the U.S. has been forced to use more costly transportation routes through Russia and Central Asia. Panetta has estimated the cost at an extra $100 million a month. He warned that it could get more expensive as the U.S. starts to withdraw equipment in advance of the 2014 troop drawdown in Afghanistan.
According to the Pentagon, the agreement is likely to free up millions of dollars in coalition support claims that can now be paid to Pakistan. The Defense Department must notify Congress first. There have been no decisions yet on any future claims.