Russia said Thursday that its military had destroyed more than 70 military targets including 11 airfields in Ukraine.

"As a result of strikes carried out by the Russian armed forces, 74 Ukrainian military ground facilities were destroyed," said Igor Konashenkov, a defense ministry spokesman, specifying that destroyed facilities included 11 airfields. He said a Ukrainian military helicopter and four drones had also been shot down.

The Russian military launched the much-anticipated invasion of Ukraine earlier on the same day, as President Vladimir Putin ignored international condemnation and sanctions and threatened 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 a Russian invasion that could cause massive casualties and topple Ukraine’s democratically elected government. Russian military columns crossed the border into Ukraine toward Chernihiv, Kharkiv and Luhansk regions, Ukrainian border guard service said in what appears to be an assault along the entire border with Russia.

Seven soldiers died in Russian airstrikes in the first few hours of the invasion, Ukraine’s Interior Ministry said.

The head of the Ukrainian military said Thursday he had received orders from President Volodymyr Zelenskyy to repel the Russian invasion of his country.

"The supreme commander the Armed Forces of Ukraine gave orders to inflict maximum losses against the aggressor," Commander-in-Chief of the Armed Forces of Ukraine, Major General Valeriy Zaluzhny said.

Earlier on Thursday, Zelenskyy introduced martial law, saying Russia has targeted Ukraine’s military infrastructure and explosions are heard across the country. Zelenskyy said he had just spoken to President Joe Biden and the United States was rallying international support for Ukraine. He urged Ukrainians to stay home and not to panic.