The U.S. and NATO believe that Belarus could "soon" join Russia in its war against Ukraine, U.S. and NATO officials tell CNN, and that the country is already taking steps to do so.



It is increasingly "likely" that Belarus will enter the conflict, a NATO military official said on Monday. "(Russian President Vladimir) Putin needs support. Anything would help," the official explained.



A Belarusian opposition source said that Belarusian combat units are ready to go into Ukraine as soon as in the next few days, with thousands of forces prepared to deploy.



In this source's view, this would have less of an impact militarily than it will geopolitically, given the implications of another country joining the war.



A senior NATO intelligence official said separately that the alliance assesses that the Belarusian government "is preparing the environment to justify a Belarusian offensive against Ukraine."



US and European sanctions in response to the war have targeted both Russian and Belarusian officials, including Belarusian President Alexander Lukashenko.



Belarus moved to change its constitution last month to allow the country to host both Russian forces and nuclear weapons permanently, though US officials have emphasized to CNN that they have not yet seen any evidence of Russia moving nuclear weapons or preparing to.



The sources emphasized that there have been no indications to date that Belarus is currently participating in the fighting in Ukraine, and a senior US defense official said the Pentagon had not seen "any indications that the Belarusians are preparing to move in -- into Ukraine or that they have made any agreements to do that."



The NATO military official said that a final decision for Belarus' involvement in the war still has to be made in Moscow, as of yet there has been no indication that Belarusian forces are participating in the fighting in Ukraine.



"It is not about what Lukashenko wants," the official explained. "The question is: does Putin want another unstable country in the region?"



"Involvement would destabilize Belarus," the official said.