The U.S. has told Russia the general locations of U.S. Special Forces advisor teams in Syria and agreed not to fly near Russian bases in Syria despite repeated Pentagon denials of cooperation with Moscow, U.S. officials said Thursday.

The surprising admission that the U.S. military had a separate track for negotiating with the Russian Defense Ministry beyond the Memorandum of Understanding (MOU) signed last year to "deconflict" aircraft was first disclosed by Air Force Lt. Gen. Charles Q. Brown, Jr., commander of U.S. Air Forces Central Command.

"There are some areas we have talked to [the Russians] about" where Special Forces teams in northeastern Syria have been have been advising rebel groups backed by the U.S. in the campaign against the Islamic State of Iraq and Syria (ISIS), Brown said in a video briefing to the Pentagon from his headquarters in Qatar.

"We have talked to them about that" to limit the risk that U.S. troops might be hit by Russian airstrikes, Brown said. "We've told them these are areas that we have coalition forces in - general areas where we have coalition forces. We don't want them to strike there because all it's going to do is escalate things. And I don't think the Russians want to escalate against the coalition."

In return, the Russians have identified airfields in Syria "that they don't want us flying close to," Brown said. Russia has maintained airfields near the northeastern Syrian city of Latakia since starting its bombing campaign last Sept. 30. Brown said those airfields are beyond where U.S. planes normally operate, "so that hasn't been an issue."

In response to followup questions after Brown's briefing, Pentagon Press Secretary Peter Cook said the talks with the Russians on Special Forces and the airfields were conducted apart from the regular contacts with the Russians on the memorandum of understanding with Moscow that were limited to "deconfliction" issues on the U.S. and Russian air campaigns over Syria.

Cook would not say who conducted the talks for the U.S. but said Defense Secretary Ashton Carter was aware of them and approved. Brown said that he was not involved. Elissa Slotkin, the acting Assistant Secretary for International Security Affairs at the Pentagon, had a main role in negotiating the MOU with Russia last year.

"I'm not going to get into details" of who negotiated and when "other than to say that there was an effort made to protect the safety of our people from the risk of Russian airstrikes," Cook said. "And that those steps were taken, and those so far have been honored."

The Pentagon has previously denied working with the Russians beyond the MOU. Carter last October, when asked by a reporter, said that there was "no intent" to discuss with Russia the deployment or whereabouts of U.S. troops to Syria, the Hill newspaper reported.

Cook said the Russians were only told in general terms of the areas where Special Forces teams were operating and not "pinpoint" locations. "There was an effort made to protect the safety of our people from the risk of Russian airstrikes," Cook said. "This was a unilateral request" by the U.S. "It was done out of an abundance of safety for our special operators."

The disclosure of the talks with the Russians on U.S. deployments came on the eve of the Feb. 19 date for a "cessation of hostilities" in Syria brokered by the United Nations with world powers, including the U.S., Russia, Iran and Saudi Arabia.

However, the forces of Syrian President Bashar al-Assad continued to press offensives north of Aleppo, Syria's largest city, with the backing of Russian airstrikes. In recent interviews, Assad has suggested that he would ignore the "cessation" until all of Syria was back under his control, bringing a rare rebuke from Russia.

In an interview with the Kommersant newspaper, Vitaly Churkin, Moscow's UN ambassador, said Assad's comments were out of line. "Russia has invested very seriously in this crisis, politically, diplomatically, and now also in the military sense," Churkin said. "Therefore, we of course would like that Bashar al Assad should take account of that."

The U.S. was also trying to rein in its allies on the ground in Syria, including the Kurdish YPG (Popular Protection Units). At a Pentagon briefing Wednesday, Army Col. Steve Warren, a spokesman for Combined Joint Task Force-Operation Inherent Resolve, said that the YPG forces in northwestern Syria were fighting with other rebel groups backed by the U.S. to seize territory before the proposed cessation of hostilities.

Turkey has also been targeting the YPG with cross-border artillery fire, fearing that the YPG was intent on setting up a Kurdish mini-state on its border.

Turkey has also blamed a YPG supporter for a suicide car bombing in Ankara Wednesday that killed at least 28. At the White House, Deputy National Security Adviser Ben Rhodes called on the YPG and other U.S.-backed groups to avoid conflict with NATO-ally Turkey.

Rhodes stressed "the importance of our alliance with Turkey," which provides support for U.S. air operations from the airbase at Incirlik, Turkey. "We want to make sure the different actors we're working with in Syria are focusing their attention where it should be, which is on the counter-ISIL effort," Rhodes said, using another acronym for ISIS.

In his briefing to the Pentagon, Lt. Gen. Brown said that a cessation of hostilities in Syria - if it takes place - would have no impact on U.S. and coalition air operations in Syria which were directed solely at ISIS. "From our perspective, it doesn't affect us," Brown said.

The ongoing fighting and relentless Russian airstrikes in Syria have mostly blocked efforts by the UN and humanitarian groups to deliver relief supplies to bombed and starving civilians.

The U.S. has thus far ruled out airdrops of relief but Brown said he could do it if asked. "We've not been asked to do that" but "we have the capability to do that," he said. "We have not had direct discussions about it. I and my staff think about it but right now we have not been asked to offer any support" by way of airdrops.

Note: This is an update of an earlier story.

--Richard Sisk can be reached at Richard.Sisk@Military.com.