MOSCOW -- Russia has vowed to respond to an unprecedented international rebuke. More than 25 countries have announced they are expelling Russian diplomats. The U.S. ordered 60 Russians to leave and will close the Russian consulate in Seattle.

The coordinated action is in response to the escalating feud over a nerve agent attack on a former Russian spy and his daughter in Britain. In addition to their own diplomatic expulsions, the Russians are considering which consulate to close there. It's fast becoming the most serious diplomatic crisis since the Cold War, reports CBS News correspondent Charlie D'Agata.

Former U.S. ambassador to Russia Bill Burns say the U.S. reaction may also indicate a changing stance on Russia from President Donald Trump.

"It seems to me it's the end of an illusion. In a sense, the illusion under which President Trump seems to have operated for a while. The illusion that you could do some kind of a grand bargain with Putin's Russia," Burns told CBS News.

The Kremlin has already vowed to respond in kind to the expulsion of 60 suspected spies from the U.S. – unprecedented numbers and an unexpectedly hard line from a Trump administration that has been reluctant to square off against president Vladimir Putin.

It's a show of solidarity for Britain and retaliation for what British Foreign Secretary Boris Johnson called "an unacceptable pattern of behavior from Russia."

"It manifests itself across the globe, from Syria to Salisbury and people have had enough of it," Johnson said.

The retaliation over what Johnson has called a pattern of antagonistic Russian behavior, going back years, continued on Tuesday. NATO chief Jens Stoltenberg announced in Brussels that the trans-Atlantic body was expelling seven Russian representatives and shrinking the overall Russian delegation from 30 to 20.

It is collective retribution for a litany of Russian transgressions against the West, including annexing Crimea, the ongoing military conflict with Ukraine, suspected meddling in foreign elections -- including the 2016 U.S. presidential election -- and President Putin's boasts of new nuclear weapons capable of striking the U.S.

On Tuesday morning Russian Foreign Minister Sergey Lavrov condemned the diplomatic expulsions as a small group of countries giving into "blackmail" by the United States. He also said there should be no doubt that Russia will respond in kind, saying no one would put up with such "thuggish" behavior, and Russia certainly wouldn't.