WASHINGTON: America's relationship with Pakistan has been battered by a string of recent setbacks, but a top US general said on Wednesday that the fact that the two countries have finally started talking again is at least a positive sign.

Marine Gen. John Allen, the top US commander in Afghanistan, cautioned that ''we need to be careful about overstating the progress that we're making, but I think that we've made real progress in the last several weeks with respect to having conversations with Pakistan we were not even having before.''

It was telling, however, that Allen could point to no concrete improvements in US-Pakistan relations, or even hint at any movement in the negotiations to open the ground supply routes into Afghanistan.

Pakistan shut down the supply routes six months ago after US airstrikes accidentally killed 24 Pakistani soldiers at two border posts.

After months of stalemate, Pakistani leaders last week signaled that negotiations on the supply routes were progressing, just in time to secure an invitation to the weekend Nato summit in Chicago.

But since then officials have acknowledged that the two sides have yet to forge an agreement or settle on new, higher fees Pakistan wants for the Nato supply convoys.

Meanwhile in Pakistan on Wednesday, a Pakistani doctor who helped the US track down Osama bin Laden was sentenced to 33 years in prison for conspiring against the state.

US officials have called for the doctor, Shakil Afridi, to be released, insisting that his assistance was an act against al Qaeda, not against Pakistan.

The latest problems don't suggest the relationship with Pakistan is deteriorating, Allen said during a Pentagon briefing, but he agreed that doesn't mean things are back on track.

He added that the supply route closures have not hampered his ability to fight the war. By using northern ground routes that skirt Pakistan, plus air cargo flights, the military was able to avoid coming running low on supplies.

Allen said there was a dip in surplus gasoline, but it didn't go below a 30-day supply.

Asked about US troop withdrawals from Afghanistan, Allen said he will begin ''very shortly'' to start pulling out some of the 23,000 troops that must be out by the end of September.

That will leave about 68,000 American military personnel in Afghanistan    Officials have said the bulk of the 23,000 probably will not come out until shortly before the deadline. As those troops come out, he said, Afghan forces will be used to fill in the gaps in the eastern and southwestern parts of the country. They will be buttressed by US advisory teams that will work with the Afghan units.

Once the 23,000 US troops are out, he said he will review how the fighting season is going and will then begin to put together an analysis for President Barack Obama on how troop withdrawals will proceed next year.

''We're going to need combat power, I don't think anyone questions that,'' Allen said, referring to 2013.

But he said some of the combat power will be Afghan forces or troops provided by other Nato nations.

US combat troops are slated to be out of Afghanistan by the end of 2014.