KYIV, Ukraine (NewsNation Now) — Russian troops launched their anticipated attack on Ukraine on Thursday, as President Vladimir Putin cast aside international condemnation and sanctions and warned other countries that any attempt to interfere would lead to “consequences you have never seen.”

The invasion began with big explosions before dawn in Kyiv, Kharkiv and Odesa as world leaders decried the start of an invasion that could cause massive casualties, topple Ukraine’s democratically elected government and threaten the post-Cold War balance on the continent.

Ukraine’s leadership said at least 40 people have been killed and dozens are wounded so far in what it called a “full-scale war” targeting the country from the east, north and south.

Ukrainian President Volodymyr Zelenskyy said Thursday the country has severed diplomatic relations with Russia. He says the nation’s security is top priority.

“The army and national solidarity are the mainstay of Ukrainian statehood,” Zelenskyy said. “Our military needs this support … The future of our Ukrainian people depends on every citizen. Everyone who has combat experience and can join the defense of Ukraine.”

NATO’s chief said the “brutal act of war” shattered peace on the European continent, as the U.S.-led alliance mobilized more troops to move toward eastern Europe.

“A full-scale war in Europe has begun,” Ukrainian presidential adviser Mykhailo Podolyak said. “Russia is not only attacking Ukraine, but the rules of normal life in the modern world.”

The announcement comes as the organization agreed to increase land, sea, and air forces on the eastern flank near Ukraine and Russia to maintain full support “for the territorial integrity and sovereignty of Ukraine within its internationally recognized borders, including its territorial waters.”

The Ministry of Internal Affairs of Ukraine announced Thursday an Armed Forces of Ukraine plane crashed with 14 people on board. Five people have died.

World leaders have decried the attack, which could cause massive casualties, topple Ukraine’s democratically elected government, upend the post-Cold War security order and result in severe economic impact around the world from soaring heating bills to spikes in food prices.

“We woke up in a different world today,” Germany’s foreign minister said, as NATO agreed to beef up air, land and sea forces on its eastern flank near Ukraine and Russia.

President Joe Biden pledged new sanctions to punish Russia for the aggression that the international community had expected for weeks but could not prevent through diplomacy. The president plans to address the country later Thursday.

Zelenskyy in an announcement called the incursion “an unjustified deceitful and cynical invasion” and declared martial law. He later asked via Twitter to “close airspace,” which NewsNation’s Leland Vittert interpreted as asking the West to impose a no-fly zone.

“Ukrainians will never give up their freedom and independence to anyone,” Zelenskyy stated. “Only we, all citizens of Ukraine, have been determining our future since 1991. But now the fate of not only our state is being decided, but also what life in Europe will be like.”

The outlook for Ukraine is bleak. Retired Lt. Gen. Richard Newton said the Ukrainian forces are “not a match” for the Russia army. Newton, speaking on a special edition of “NewsNation Prime,” predicted Ukraine could fall to the Russian military in about four days, and thought Russia could have air superiority in the country within a matter of hours.

In the early-morning hours of Thursday in Ukraine, smoke could be seen rising from the capital, and later on air-raid sirens rang through the city, which turned out to be a drill. Some journalists donned flak jackets and helmets as they delivered live reports.

Russia has launched attacks in 10 Ukrainian regions, primarily in the east and south of the country, Ukraine’s state emergency service stated. Residents in Kyiv and other cities were ordered to bomb shelters.

Associated Press journalists in the cities of Odesa and Kharkiv were also hearing explosions.

Andrij Dobriansky, communications director for the Ukrainian Congress Committee of America, said sanctions, and threats thereof, were unlikely to work against Putin.

“Action is what’s needed and unfortunately, the world decided to act at the very last minute,” Dobriansky said on “NewsNation Prime.” He called Putin a “war criminal” for his invasion of Ukraine.

U.S. Rep. Mark Green (R-Tenn), told NewsNation’s Leland Vittert: “This is a full-scale invasion of a sovereign nation.”

“This is a strategic attack, a targeted attack. But it is a full-scale war,” Green said Wednesday night. “This is an invasion of the entire country of Ukraine.”

The consequences of the conflict and resulting sanctions levied on Russia could reverberate throughout the world.

Stock markets plunged and oil prices surged by nearly $6 per barrel after the invasion. The ruble sank 7.5 percent to more than $87 to the U.S. dollar. Market benchmarks in Tokyo and Seoul fell 2 percent and Hong Kong and Sydney lost more than 3 percent Thursday.

More sanctions were coming. The European Union on Thursday said it was planning the “strongest, the harshest package” of sanctions it has ever considered at an emergency summit.