(CNN) Russian satellites have been exhibiting the "unusual and disturbing behavior" of following a US satellite in orbit, according to the commander of the Space Force, the newest military service.

"Last November the Russian government launched a satellite that subsequently released a second satellite," US Space Command Commander and the Space Force's Chief of Space Operations Gen. John Raymond said in a statement Monday.

"These satellites have been actively maneuvering near a U.S. government satellite and behaving similar to another set of satellites that Russia deployed in 2017, and which the Russian government characterized as 'inspector satellites.' "

Raymond's comments mark the first substantive statement from the Space Force and come as the US has become increasingly concerned about what adversaries are doing in space -- one of the reasons why the US launched the new military branch , the first new military service since 1947, in December. The Trump administration requested $18 billion for the Space Force and other space activities on Monday as part of its Pentagon budget.

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