Vladimir Putin says he will consider retaliating after Washington hit Russia with sanctions over alleged hacking during the U.S. presidential election.
Among the measures 35 Russian diplomats have been given 72 hours to leave the country.
US intelligence agencies are now convinced that Russia was behind the interference
President Barack Obama says the hacks could only have been directed by the upper levels of the Russian government.
Incoming US President Donald Trump is keeping quiet on the issue for the time being, and says he's going to meet with intelligence chiefs next week to try to get the facts about the allegations.