Russia-Ukraine News Highlights: PM Narendra Modi speaks to Russian President Vladimir Putin

also vowed retaliation against those who interfere with Russian-Ukraine operation. Explosions were heard in Kharkiv, a major Ukrainian city just south of the Russian border, after Moscow launched the military operation. Ukrainian forces in the city have been battling Moscow-backed insurgents since 2014

US President Joe Biden said the "world will hold Russia accountable" over its attack on Ukraine that he warned will cause "catastrophic loss of life."

Putin will face significant consequences if Moscow invades Ukraine, the White House warned on Wednesday, noting that the series of sanctions announced against it in the last two days are just a beginning.

Weeks of diplomacy to avert war and sanctions on Russia failed to deter Putin, who has massed over 150,000 troops on the Ukraine border.

Airlines should stop flying over any part of Ukraine because of the risk of an unintended shootdown or a cyber attack targeting air traffic control amid tensions with Russia, a conflict zone monitor said.