To be sure, Obama officials have low expectations about the prospects for constructive dealings with Putin, who has pursued an aggressive foreign policy while clamping down on dissent at home. They are also outraged by what they believe to be a Kremlin’s hand in the cyber theft and release of Democratic National Committee emails. (Kerry sternly raised the issue with Lavrov on Tuesday, U.S. officials said.) And Slotkin made clear that Washington’s offers of dialogue are part of a “balance” that includes military muscle-flexing and steps like recent U.S. reinforcements of NATO’s eastern flank. “We have to have a twin deter-and-dialogue message,” Slotkin said.

But some Democratic national security veterans fear that a potentially dangerous level of hostility to Russia has emerged in recent weeks. They say the growing rivalry between Washington and Moscow, stoked by campaign rhetoric aimed at discrediting Trump, may be taking on a life of its own, making global problems harder to solve and increasing the risk of an accidental conflict—potentially even a nuclear one.

“We’re sleepwalking into a new Cold War,” said William Perry, who served as Secretary of Defense under Bill Clinton from 1993 to 1996, an era of relatively warm relations between the U.S. and Russia. “There’s hardly any debate about it, and the public doesn’t understand the danger.”

Perry said he is particularly concerned that poor communication, an arms buildup on both sides, and jangled nerves increase the possibility of an accidental or unintentional nuclear confrontation.