KEY POINTS
  • There have been reports of a Russian troop buildup on Ukraine's border for weeks.
  • While it aspires to membership, Ukraine is not a member of either the EU or NATO, however, and NATO is under no obligation to defend the country.
  • As such, just how far the U.S. and EU might go to protect the country is uncertain.
Russian President Vladimir Putin waves during the US - Russia Summit 2021 at the La Grange Villa near the Geneva Lake, on June 16, 2021 in Geneva, Switzerland.

Relations between the U.S. and Russia, which are already tense, took another turn for the worse Wednesday after Russia said it was ordering U.S. Embassy staff who have been in Moscow for more than three years to fly home by the end of January.

It said it had resorted to "retaliatory measures" after the Russian ambassador to the United States, Anatoly Antonov, said 27 Russian diplomats and their families would have to leave the U.S. on Jan. 30, and another 27 diplomats would need to depart by June, because their visas have not been extended by the American authorities.