Editor's Note: This article originally appeared on Business Insider.

Russian spacecraft are trailing a U.S. satellite used to spy on other countries, the commander of the US Space Force told TIME Magazine.

The two Russian satellites have come within 100 miles of the U.S. satellite and the United States has raised concerns about the matter to Moscow through diplomatic channels, Space Force Commander Gen. John Raymond told
TIME Magazine's W. J. Hennigan.

“We view this behavior as unusual and disturbing,” Raymond told the publication. “It has the potential to create a dangerous situation in space,” he said.

A Pentagon spokesperson was not immediately available to confirm the report. The Russian Embassy in Washington did not respond to a request for comment.

The move comes amid political tensions between the two countries, from election-meddling to ongoing tensions in Ukraine and Syria.

The Russian satellites' maneuvering was spotted by Michael Thompson, a satellite and spacecraft enthusiast, who wrote on Twitter that “this is all circumstantial evidence, but there are a hell of a lot of circumstances that make it look like a known Russian inspection satellite is currently inspecting a known U.S. spy satellite.”

The Russian Defense Ministry said in December that a maneuver by the satellites — in which one satellite “birthed” another resulting in two satellites — was an experiment to assess the “technical condition of domestic satellites,” according to the Russian news agency TASS.

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