President Trump said the Russian government told the U.S. that "most of their people" stationed in Venezuela have left the crisis-stricken South American country.

"Russia has informed us that they have removed most of their people from Venezuela," the president wrote on Twitter Monday afternoon during his state visit to the U.K.

The State Department did not respond to a request by CBS News to clarify when and how the Russian government informed the U.S. of a personnel withdrawal in Venezuela. CBS News also asked the department to identify the information on which the president based his assertion on and to clarify what exactly Mr. Trump was referring to when he wrote "people."

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Mr. Trump's assertion — if true — would represent a significant development in the political showdown in Venezuela, where the government of Nicolás Maduro has embraced the support of Russia and other U.S. adversaries like Cuba and China to fend off a leadership challenge by National Assembly President Juan Guaidó.

Since backing Guaidó's bid to oust Maduro in January, the Trump administration and lawmakers in Congress have repeatedly denounced Moscow's economic and military ties to the socialist government in Caracas.

National Security Adviser John Bolton, a hawk on security issues, has warned Russia not to interfere in the Western Hemisphere, even invoking the 19th century Monroe doctrine, which outlined U.S. opposition to European colonialism in Latin America.

The invocation of the centuries-old term — which, in Latin America, has connotations of U.S. intervention — has been denounced by Maduro and his allies around the world, who have accused the Trump administration of trying to sponsor a coup in Venezuela. More than 50 mostly Western governments have vouched their support for the Venezuelan opposition, but the military has remained loyal to the ruling leftist government.