A communications line created between the militaries of the United States and Russia at the start of Moscow's war against Ukraine has been used only once so far, a US official told Reuters.
The official, who spoke on condition of anonymity, said that the United States initiated a call through the "de-confliction" line to communicate its concerns about Russian military operations near critical infrastructure in Ukraine.
Reuters is the first to report on the use of the de-confliction line, beyond regular testing.
Few details are known surrounding the specific incident that led to the call on the line, which connects the US military's European Command and Russia's National Defense Management Center.
The official declined to elaborate but said it was not used when an errant missile landed in NATO-member Poland on Nov. 15, killing two people. The blast was likely caused by a Ukrainian air defense missile but Russia was ultimately responsible because it started the war in late February, NATO said.
Although the US official declined to specify which Russian activity raised the US alarm, there have been publicly acknowledged incidents involving Russian fighting around critical Ukrainian infrastructure.
These include Russian operations around Ukraine's Zaporizhzhia nuclear power plant, Europe's biggest, which is under Russian control.
Ukraine has also voiced concerns Russia might blow up the Nova Kakhovka dam, which holds back an enormous reservoir in southern Ukraine. Bursting the dam would send a wall of water flooding settlements below, including towards the strategic regional capital Kherson, which Ukrainian forces recaptured on Nov. 11.
US-Russia communications have been in the spotlight since the start of Russia's invasion of its neighbor, given the grave risk that a miscalculation by either side could cause a direct conflict between the nuclear-armed nations.
Several ways to communicate
The de-confliction line is just one of several ways the US and Russian militaries still have to communicate.
Other military channels include rare high-level talks between US Defense Secretary Lloyd Austin and Russian Defense Minister Sergei Shoigu. The top US and Russian generals, US Army General Mark Milley and Russian General Valery Gerasimov have also spoken on two occasions since the war started, his office said.
White House national security adviser Jake Sullivan and CIA Director Bill Burns have also had contact with Russian officials.
Still, US-Russia relations are at their lowest point since the Cold War and the US State Department said on Monday that Moscow postponed talks in Cairo aimed at resuming nuclear weapons inspections. The Russian foreign ministry confirmed the talks were postponed. Neither side provided a reason.
Asked for comment on the de-confliction line, the Pentagon said only that it retained several channels to "discuss critical security issues with the Russians during a contingency or emergency for the purposes of preventing miscalculation, military incidents, and escalation."
"We are encouraged by recent senior DoD calls with Russian counterparts and believe continued dialogue is critical," a Department of Defense spokesperson said.
Neither Russia's embassy in Washington nor its defense ministry in Moscow responded to requests for comment.
Not a 'complaint' line
When it was announced in March, the Pentagon said the de-confliction line was created to avoid any inadvertent clashes in NATO airspace or on the ground.
"It's not meant to be an all-purpose complaint line where we can just pick up the phone and register concerns about what Russia's doing in Ukraine," a senior US defense official said at the time.
During the Cold War, the United States and the Soviet Union maintained such hotlines at different levels.
Alexander Vershbow, a former US ambassador to Moscow and a former senior Pentagon and NATO official, said the latest deconfliction line was meant to focus on daily operations - as opposed to the more strategic conversations between top officials like Milley and Gerasimov.
"We've seen this in Syria, where having the direct operational channel can at least clarify intentions during a fast-moving situation where maybe Washington is asleep,"
Alexander Vershbow, former US ambassador to Moscow and former senior Pentagon and NATO official
Vershbow drew a comparison to the far more active deconfliction line for Syria, where US and Russian military forces sometimes operate in the same airspace or terrain.
"We've seen this in Syria, where having the direct operational channel can at least clarify intentions during a fast-moving situation where maybe Washington is asleep," Vershbow told Reuters.
The deconfliction line is tested twice daily with calls conducted in Russian, the US official told Reuters. A Russian speaker from the US European Command initiates those calls out of Wiesbaden, Germany, the official said.
Wiesbaden is also the location of the Pentagon's new Security Assistance Group-Ukraine, or SAG-U, which remotely supports the Kyiv government's defense against Russian troops.
US officials, speaking on condition of anonymity, have previously said that early in the conflict planners believed the de-confliction line could be useful if the United States needed to evacuate Americans from Russian-occupied territory in Ukraine.
When the war began, the United States thought Russia might be able to quickly capture Ukrainian territory, trapping American citizens before they had a chance to leave.
One official had speculated it also could have been used if a Russian fighter jet chased a Ukrainian aircraft into Polish airspace, or if a Russian missile crossed NATO airspace.