Joe Biden warns Vladimir Putin against Ukraine invasion

President Joe Biden (AP Photo/Evan Vucci)

Joe Biden has vowed to make it “very, very difficult” for Russian President Vladimir Putin to take military action in Ukraine, saying his administration is putting together a comprehensive set of initiatives to curb Russian aggression.

The US president offered the measured warning to Mr Putin amid growing concern about a Russian build-up of troops on the Ukrainian border and increasingly aggressive rhetoric from the Kremlin.