Europe's defenses will be supported, the U.S announced on Wednesday in the wake of Russia's invasion of Ukraine, as NATO leaders voiced Moscow as the greatest threat to the West.

Meeting in Madrid, alliance leaders said Russia "is the most significant and direct threat to allies' security and peace and stability in the Euro-Atlantic area."

This came as NATO welcomed Sweden and Finland as invitees to join the alliance and U.S. President Joe Biden announced new deployments of U.S. troops, ships and planes.

Biden boasted the U.S. announcement was exactly what President Vladimir Putin "didn't want" and Moscow, facing fierce resistance from Ukrainian forces equipped with Western arms, reacted with predictable fury.

Deputy Foreign Minister Sergei Ryabkov denounced the U.S. military buildup and warned NATO members that the shifting balance of power "would lead to compensatory measures on our part."

"I think that those who propose such solutions are under the illusion that they will be able to intimidate Russia, somehow restrain it – they will not succeed," he said.

NATO leaders have funneled billions of dollars of arms to Ukraine and faced a renewed appeal from President Volodymyr Zelenskyy for more long-range artillery.

"Ukraine can count on us for as long as it takes," NATO chief Jens Stoltenberg said, announcing a new NATO strategic overview that focuses on the Moscow threat.

"We cannot discount the possibility of an attack against allies' sovereignty and territorial integrity," the document, updated for the first time since 2010, said.

In a summit statement, they said: "Russia's appalling cruelty has caused immense human suffering and massive displacements, disproportionately affecting women and children."

Zelenskyy had earlier addressed the NATO chiefs by videoconference, calling for stricter economic sanctions, but afterward his foreign minister Dmytro Kuleba thanked Ukraine's western friends.

Today in Madrid, NATO proved it can take difficult but essential decisions. We welcome a clear-eyed stance on Russia, as well as the accession for Finland and Sweden," he said.

"An equally strong and active position on Ukraine will help protect Euro-Atlantic security and stability."

As Western leaders met in Madrid, Ukraine officials complained that Russian missiles had hit civilian housing and businesses in and around the cities of Dnipro, Mykolaiv, and Kharkiv, leaving at least seven dead and 14 wounded.

In Kremenchuk, the town where a Russian missile on Monday destroyed a shopping center and – according to local officials – killed at least 18 civilians, clearing operations continued.

A giant crane was working near the site of the impact and in the rubble-strewn parking area shopping trolleys piled with clothes and household goods lay abandoned.

Western leaders have dubbed the Kremenchuk strike a war crime, and Zelenskyy has demanded that U.N. investigators visit. Russia says it hit a depot storing Western arms.

The Russian defense ministry said it had inflicted severe casualties on Ukrainian troops defending the town of Lysychansk, in the eastern Donbass region, and said the Kharkiv attack had hit Ukrainian command centers and a training base for foreign mercenaries.

Moscow's Feb. 24 invasion of pro-Western Ukraine triggered massive economic sanctions and a wave of support for Zelenskyy's government, including deliveries of advanced weapons.

At NATO, two formerly military nonaligned European countries – Sweden and Russia's north-western neighbor Finland – will be accepted as candidates and Washington has announced that it will shift the headquarters of its 5th Army Corps to Poland.

An army brigade will rotate in and out of Romania, two squadrons of F-35 fighters will deploy to Britain, U.S. air defense systems will be sent to Germany and Italy, and the fleet of U.S. Navy destroyers in Spain will grow from four to six.

"That's exactly what he didn't want but exactly what needs to be done to guarantee security for Europe," Biden said, of Putin's efforts to roll back Western influence and reestablish influence or control over territories of the former Russian empire.

Sweden and Finland's path to NATO membership was opened after President Recep Tayyip Erdoğan agreed to lift Turkey's veto – the ally accuses Stockholm and Helsinki of harboring wanted PKK/YPG and Gülenist Terror Group (FETÖ) terrorists.

Turkey announced Wednesday that it would request the extradition of 33 alleged terrorists under the terms of the agreement signed Tuesday with Sweden and Finland to allow them to make membership bids.

A sanctions task force of leading Ukraine allies has frozen more than $330 billion in financial resources owned by Russia's elite and its central bank since Moscow's invasion, it announced Wednesday.

The Russian Elites, Proxies and Oligarchs Task Force (REPO) said the allies had blocked $30 billion in assets belonging to Russian oligarchs and officials and immobilized $300 billion owed by the Russian central bank.

Norway said it would donate three multiple-launch rocket systems to Ukraine, following similar decisions made by Britain, Germany and the U.S.