Moscow( CNN) US House Speaker Nancy Pelosi's announcement of a formal impeachment investigation of President Donald Trump on Tuesday has defined the stage for an intensely partisan fight in Washington.

The Kremlin thus far has refrained from commenting on the Beltway political crisis. Dmitry Peskov, Putin's spokesperson, said Tuesday Moscow was simply “observing another series of internal American political frictions, ” almost as if he were describing a new season of “House of Cards.”

But Putin is not a passive commentator in the Ukraine drama. At the center of the political storm in Washington is a major accusation: That Trump threatened to withhold military aid to Ukraine unless it opened an investigation into Democratic front-runner Joe Biden and his son.