Burns issued his warning at a meeting with his Russian counterpart Sergei Naryskin in Ankara, Turkey on Monday, the US said. “It sends a message about the consequences of Russia’s use of nuclear weapons and the risks of escalation to strategic stability,” the White House said Monday. Burns’ meeting with foreign spy chief Naryshkin – the first confirmed high-level in-person contact between the US and Russia since Russia’s full-scale invasion of Ukraine began in February – comes at a tense time in the war. US officials have raised concerns that Putin could use a tactical nuclear weapon or other weapon of mass destruction on the battlefield, particularly as Russian forces continue to face military setbacks. Russian forces withdrew from Kherson last week, depriving Putin of the only regional capital captured during the nine-month invasion. The Russian president also faces the prospect of losing a territory he annexed in a Kremlin ceremony in September. When he announced the annexation, Putin said Moscow would use “all means at its disposal” to protect its new territories – and made veiled threats to use nuclear weapons to do so. But Putin’s escalation has failed to deter Ukraine, whose better-equipped, larger force continued to recapture territory days after Putin claimed it was part of Russia. The loss of Kherson – which Russia has sought to describe as a “maneuver” rather than a humiliating withdrawal – is one of Moscow’s biggest setbacks to date. Dmitry Peskov, Putin’s spokesman, said he could “only” state that Kherson was “the territory of the Russian Federation” on Monday as Ukrainian President Volodymyr Zelensky visited the city to a rapturous welcome from soldiers and locals who they had spent months living in possession. Russian forces had captured the provincial capital in March. Nuclear tensions escalated last month after Russia accused Ukraine of preparing to use a crude explosive device with radioactive material known as a dirty bomb, sparking fears that Moscow may stage a “false flag attack” that will be blamed on Kyiv. But US officials said fears were allayed after a phone call between Western defense chiefs and their Russian counterpart, Sergei Shoigu. Speaking at a conference last month, Putin said Russia would not use nuclear weapons in Ukraine because it had “no military or political logic” to do so, even as he repeated allegations of Ukraine’s alleged dirty bomb. US national security adviser Jake Sullivan is also holding talks with senior Russian officials to try to defuse nuclear tensions, according to people familiar with the discussions. The meetings between US and Russian intelligence chiefs come as some in the Biden administration see an opportunity for possible peace talks as fighting is expected to slow down in the winter. “It will probably be static through the winter. there will be fighting, but it will be relatively static, and then there will be a window of opportunity for negotiations,” Mark Milley, chairman of the US Joint Chiefs of Staff, said last week.