By Thomas Watkins
Moscow says it will work to avert potential mishaps between Russian and US pilots flying missions over Syria, Pentagon officials say.
US and Russian officials held discussions last week at Russia's request on establishing measures to avoid accidents so warplanes flying over Syria would not be in the same place at the same time.
The so-called "deconfliction" talks came after Russia started bombing in support of Syrian President Bashar al-Assad, further complicating the four-and-a-half-year conflict.
But despite Russian violations of Turkish air space at the weekend, Moscow has not participated in further talks, frustrating US military officials who'd made repeated overtures.
US Defense Secretary Ashton Carter has spoken repeatedly in recent days about Russia's "irresponsible and unprofessional" moves in Syria.
Moscow on Tuesday (local time) seemed to respond to those remarks.
A senior defence official, speaking during a European tour by Carter, said Moscow had indicated it was open "in principle" to carrying out pledges made during the first round of talks.
Officials have said these commitments could include undertakings on which language Russian and American pilots will use for communication, the choice of radio frequency for distress calls, and the altitude at which warplanes will operate.
"We look forward to the formal response from the Russians and learning the details. We stand ready to meet again to continue our earlier discussion as soon as possible," Pentagon press secretary Peter Cook said.
Turkey says Russian fighter jets violated its air space near the Syrian border on Saturday and Sunday, further heightening tensions.
On Tuesday, it said that eight Turkish F-16 jets, carrying out reconnaissance flights over the Turkish-Syrian border a day earlier, were held on radar lock by an unidentified MiG-29.
Radar lock enables a warplane's missile systems to automatically follow a target.
Carter said violations of Turkish airspace would "cause us further to strengthen our posture with respect to Russia" although he did not elaborate.
The Pentagon has repeatedly stressed Russia's involvement in Syria would not alter continued air strikes against Islamic State jihadists there and in Iraq as part of a coalition of more than 60 nations.
Russia said it was not planning to send ground troops to fight IS jihadists in Syria and will not support Russian volunteers willing to take part in the conflict.
"This is not the government's role," Kremlin spokesman Dmitry Peskov said on Tuesday.
President Vladimir Putin is not focused on the possibility of Russian citizens joining the ranks of the Syrian army to support Assad's beleaguered regime, Peskov said.
"This is not a topic on the agenda right now," he told Russian news agencies.
Russia already has at least 2000 military personnel in Syria, Pentagon officials say. They are stationed at an air base in the Latakia region in the country's northwest.
Meanwhile Russian jets carried out air strikes on 12 Islamic State sites in Syria on Tuesday, the defence ministry said.
The Russian warplanes hit the region around the eastern city of Deir Ezzor and in the provinces of Damascus, Idlib and Latakia, the defence ministry said in a statement.
The ministry said the planes hit "logistical infrastructure, command posts, training camps and bases" belonging to IS jihadists in about 20 sorties.