ROME (AFP) - Russian officials have said they will work to avert potential mishaps between Russian and US pilots flying missions over Syria, Pentagon officials said Tuesday.
US and Russian officials held discussions last week - at Russia's request - on establishing accident-avoidance measures 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 for new talks.
And US Defence Secretary Ashton Carter has spoken repeatedly in recent days about Russia's "irresponsible and unprofessional" moves in Syria.
Russia on Tuesday 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.
Pentagon press secretary Peter Cook said Washington noted Russia's move.
"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," Cook told reporters accompanying Carter.
"These meetings were their initiative in the first place, focused on professional conduct. It's only professional that you follow through on the requests they made and they've not done that yet," Carter said - before the latest developments - after addressing troops at a Spanish-US air base at Moron de la Frontera in southern Spain.
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.
'STRENGTHEN OUR POSTURE'
Carter said violations of Turkish airspace would "cause us further to strengthen our posture with respect to Russia," although he did not elaborate.
"It's further evidence that they are not thinking things through very well," he said.
The Pentagon has repeatedly stressed Russia's involvement in Syria would not alter continued air attacks against Islamic State in Iraq and Syria (ISIS) militants there and in Iraq as part of a coalition of more than 60 nations.
Carter could not confirm reports Moscow was committing "volunteer" ground troops to fight in Syria, but said if true, "that would simply be deepening their mistake".
Russia already has at least 2,000 military personnel in Syria, Pentagon officials say. They are stationed at an air base in the Latakia region in the country's northwest.
A defense official told AFP that Russia had moved artillery and helicopters to support potential operations in the areas of Latakia, Homs and Mara.
Carter visited Sigonella, a US-Italian base in Sicily, after stopping at Moron de la Frontera, where the United States and Madrid have agreed the permanent establishment of a force of 2,200 US marines.
Carter's five-day trip to Spain, Italy, Britain and a Nato ministerial meeting in Brussels is intended to recognise the work of ally nations as they scramble to tackle the refugee crisis sparked by Syria and react to new threats on Nato's "Southern Flank," including unrest in North Africa.
The tour comes at a fraught time for Carter, who started in the Pentagon's top job in February and who faces pressure at home over Syria and a simmering scandal involving military officials allegedly cherry-picking intelligence.
He meets with leaders in Rome on Wednesday, including the president and defence minister.