Pentagon officials have in recent weeks asked several NATO countries to tone down their rhetoric regarding the threat posed by Russia, arguing that some statements by European leaders and officials have undermined continental security, four people familiar with the matter said, Reuters reports.

Among the nations that have received messages urging them to keep public statements in check are Lithuania, Latvia and Estonia, said the people.

Among the comments that have drawn US officials' attention are suggestions by European leaders that Russia is cornered and resorting to increasingly desperate measures as its invasion of Ukraine slows to a crawl, one of the people said.

Pentagon policy chief Elbridge Colby, a key figure in an ongoing review of US troop levels in Europe, was one of the US officials delivering the message, the people said.

One of the people familiar told Reuters that Colby told a Baltic official recently that there should be no "poking" directed at the Russians.

The person said Colby pointed to Europeans publicly suggesting that Russia was "cornered like a rat" as an example of unhelpful rhetoric.

"We are helping you. The Americans are there," said a separate European official, describing the Pentagon's recent private messaging. "Just don't be loud. Don't make noise."

None of the people, who include three European officials and a US official, suggested the advice was communicated in a confrontational manner.

One of the European officials said that the Pentagon's advice, while cordial, was baffling.

Asked for comment, a Pentagon official said: "Private conversations among allies are just that, so we will not comment on these allegations."