"Sham" referendums being held in four areas of Ukraine could provide Russia a pretext to escalate the war in Ukraine. Here's what could happen next.

The Kremlin-orchestrated referendums concluded Tuesday, heightening tensions with Western countries that have already declared the votes illegitimate.

Russian President Vladimir Putin was appointed acting prime minister on Aug. 9 1999 by then president Boris Yeltsin. He has been in office as president or prime minister ever since, a period spanning two decades.