WASHINGTON — The U.S. Embassy in Kyiv issued a warning on Wednesday morning that Russia might launch a “significant air attack,” closing the embassy and recommending employees to shelter in place, with at least two other Western embassies—Greece and Italy—joining in.

The warning came on the day Ukraine used UK-supplied Storm Shadow cruise missiles to strike military targets inside Russia for the first time, according to media outlets citing Ukrainian and Western officials and local footage. On Tuesday, Ukrainian forces used U.S.-made ATACMS, or Army Tactical Missile Systems, to strike into Russian territory for the first time, following the long-sought green light to do so from President Joe Biden. 

Russia has so far responded with foreboding statements and a change to the country’s nuclear doctrine.

“We will be taking this as a qualitatively new phase of the Western war against Russia,” Russia’s foreign minister Sergei Lavrov said at a news conference on Tuesday. “And we will react accordingly.”

The threat came amid  Russian President Vladimir Putin’s recent changes to the country’s nuclear doctrine, lowering the threshold for the use of nuclear weapons and enshrining Russia’s right to respond to “aggression by any non-nuclear state with the participation or support of a nuclear one” in what appears to be a direct reference to the Biden administration’s action. 

As of Wednesday afternoon, no “significant air attack” has come. In a press conference, State Department spokesperson Matthew Miller said the embassy will return to normal on Thursday, but “there is always a threat” of more strikes.

Some appear skeptical about the escalation of the Russian response. 

“I think believing that Russia is somehow going to do something more than they’ve already done is a misplaced notion, just because they’re already attacking Ukraine in so many different ways,” said James Goldgeier, Brookings Institution visiting fellow.

Russia is fighting a war to destroy Ukraine, and they’re already doing everything they can to achieve this objective, so I think they’re just going to continue on,” added Goldgeier, who previously served as director for Russian, Ukrainian and Eurasian affairs in the National Security Council under President Bill Clinton.

Other experts think the Kremlin might respond with attacks outside Ukraine, alluding to the possibility of sabotage in Europe. 

“The horizontal escalation that Russia can do, especially with sabotage in Europe, is certainly something that we have to keep in mind,” said Liana Fix, a fellow for Europe at the Council on Foreign Relations.

The Kremlin has long been accused by Western officials of fighting a shadow war in Europe. Most recently, two undersea cables carrying internet data deep in the Baltic Sea were damaged this week, drawing warnings from European governments of possible Russian “hybrid warfare” targeting global communications infrastructure.

Nuclear Response

So far, Russia’s response “on paper” has been limited to the changes to nuclear doctrine, Fix added. But there appears to be an agreement among experts that Moscow will not deploy its nuclear arsenal quite yet. 

“Its credibility, when it comes to the use of nuclear weapons, is significantly damaged, and has been damaged over the last two years,” Fix added. “Russia has argued again and again that it would do it, but again and again, this has turned out a bluff, and the lower the threshold becomes in a doctrine, the more difficult it is to make this doctrine actually credible.”

Charles Kupchan, a senior fellow at the Council on Foreign Relations, agreed. 

“I don’t think the Russians are going to use nuclear weapons, even though we saw, over the last few days, a lowering of the threshold on the use of nuclear weapons,” he said. 

Goldgeier explained there isn’t “a lot of military utility” for Putin to use atomic weapons. 

“I think that the costs to Russia and to him for using nuclear weapons would just be so enormous, I think the level of international condemnation would be huge,” he said.