Russia attacks Ukraine as defiant Putin warns U.S., NATO

Russian troops launched their anticipated attack on Ukraine on Thursday, as President Vladimir Putin cast aside international condemnation and sanctions, warning other countries that any attempt to interfere would lead to 'consequences you have never seen.'

Big explosions were heard before dawn in Kyiv, Kharkiv and Odesa as world leaders decried the start of an Russian invasion that could cause massive casualties and topple Ukraine's democratically elected government.

Ukrainian President Volodymyr Zelenskyy introduced martial law, saying Russia has targeted Ukraine's military infrastructure and explosions are heard across the country. Zelenskyy said he had just talked to President Joe Biden and the U.S. was rallying international support for Ukraine. He urged Ukrainians to stay home and not to panic

Biden pledged new sanctions meant to punish Russia for an act of aggression that the international community had for weeks anticipated but could not prevent through diplomacy.

Putin justified it all in a televised address, asserting the attack was needed to protect civilians in eastern Ukraine -- a false claim the U.S. had predicted he would make as a pretext for an invasion. He accused the U.S. and its allies of ignoring Russia's demand to prevent Ukraine from joining NATO and offer Moscow security guarantees, and credulously claimed that Russia doesn't intend to occupy Ukraine but will move to "demilitarize" it and bring those who committed crimes to justice.