Police officers detain a demonstrator in St. Petersburg

Video. Dozens of anti-war protesters detained in Saint Petersburg

Russian police have detained almost 1,400 people at anti-war protests across Russia after President Vladimir Putin sent troops to invade Ukraine, an independent monitor said Thursday.

Russian police have detained almost 1,400 people at anti-war protests across Russia after President Vladimir Putin sent troops to invade Ukraine, an independent monitor said Thursday.

"More than 1,391 people have already been detained in 51 cities," said OVD-Info, which tracks arrests at opposition rallies. More than 700 people have been detained in Moscow and over 340 people in the second-largest city Saint Petersburg, the monitor said.