NATO on Wednesday pledged more support for Kyiv as it faces the onslaught from Moscow and invited Sweden and Finland to join the military alliance. The move is one of the biggest shifts in European security in decades after Russia's invasion of Ukraine pushed Helsinki and Stockholm to drop their traditional neutrality.

NATO's 30 allies decided at the summit in Madrid and also agreed to formally treat Russia as the "most significant and direct threat to the allies' security," according to a summit statement.

"Today, we have decided to invite Finland and Sweden to become members of NATO," NATO leaders said in their declaration after Turkey lifted a veto on Finland and Sweden joining.

Ratification in allied parliaments is likely to take up to a year, but once it is done, Finland and Sweden will be covered by NATO's Article 5 collective defense clause, putting them under the United States' protective nuclear umbrella.

"We will make sure we are able to protect all allies, including Finland and Sweden," NATO Secretary-General Jens Stoltenberg said on the second day of a NATO summit in Madrid said.

At the summit, NATO agreed to the longer-term support package for Ukraine, in addition to the billions of dollars already pledged in weapons and financial support.

German Chancellor Olaf Scholz said that arms would continue to be supplied to Kyiv, which seeks help to overpower Russian artillery, particularly in eastern Ukraine, where Russia is slowly advancing in a grinding war of attrition.

"The message is: We will continue to do so – and to do this intensively – for as long as it is necessary to enable Ukraine to defend itself," Scholz said.

"Ukraine can count on us for as long as it takes," Stoltenberg said.

"We'll state clearly that Russia poses a direct threat to our security," he said earlier, adding that the military alliance faces its biggest challenge since World War II amid the war in Ukraine.

Stoltenberg also said NATO allies meet "amid the most serious security crisis we have faced," as he arrived at the alliance's summit in Madrid. "This will be a historic and transformative summit."

"We will make a decision at the summit to invite Sweden and Finland to become members, that's unprecedented quick," he told reporters. Both countries applied for membership in the alliance in mid-May.

"After the invitation, we need a ratification process in 30 parliaments," he added. "That always takes some time but I expect also that to go rather quickly because allies are ready to try to make that ratification process happen as quickly as possible."

He added the alliance is going to agree on deterrence to be able to deploy more combat formations and get more pre-positioned equipment by next year in Eastern Europe.

Meanwhile, Spanish Prime Minister Pedro Sanchez, the host of this week's NATO summit, told Cadena Ser radio that Russia will be identified as NATO's "main threat" in its new strategic concept, as opposed to a strategic partner previously.

"We are sending a strong message to (Russian President Vladimir) Putin: 'You will not win,'" Sanchez said in a speech.

Allies also agreed on NATO's first new strategic concept – its master planning document – in a decade. Russia, previously classed as a strategic partner of NATO, is now identified as NATO's main threat.

Russia's invasion of Ukraine is "a direct threat to our Western way of life," Belgian Prime Minister Alexander de Croo added, citing the wider impact of the war, such as rising energy and food prices.

Since the end of the Cold War, NATO is due to launch the largest revamp of its defense and deterrence capabilities by strengthening the forces on its eastern flank and massively ramping up the number of troops it has at high readiness.

The planning document also cited China as a challenge for the first time, setting the stage for the 30 allies to plan to handle Beijing's transformation from a benign trading partner to a fast-growing competitor from the Arctic to cyberspace.

Unlike Russia, whose war in Ukraine has raised serious concerns in the Baltics of an attack on NATO territory, China is not an adversary, NATO leaders said. But Stoltenberg has repeatedly called on Beijing to condemn Russia's invasion of Ukraine, which Moscow says is a "special operation."

"China's not an adversary," Stoltenberg earlier said. "But of course, we need to take into account the consequences to our security when we see China investing heavily in new modern military capabilities, long-range missiles or nuclear weapons and also trying to control critical infrastructure, for instance, 5G."

In a sign of this shift, the leaders of partners South Korea and Japan attended a NATO summit for the first time.