• NATO chief Jens Stoltenberg on Wednesday urged Russian President Vladimir Putin to stop the war in Ukraine "immediately" and engage in diplomacy.
• Speaking at an extraordinary meeting of NATO defense ministers in Brussels, Belgium, he said the alliance had agreed to double down on its support for Ukraine via military, financial and humanitarian aid.
• However, he said NATO was unmoved on its resistance to fast-track Ukraine's application to join the alliance.

NATO Secretary-General Jens Stoltenberg on Wednesday called on Russian President Vladimir Putin to "immediately" stop the war in Ukraine, adding that Russia's efforts to undermine the alliance had failed.

"President Putin must stop this war immediately [and] engage in diplomacy in good faith," Stoltenberg said at an extraordinary meeting of NATO defense ministers in Brussels.

At the same time, he said the military alliance had agreed to double down on its support for Ukraine, providing further military supplies, financial help and humanitarian aid.

Stoltenberg added that member states would expand their defenses across land, air, sea and space in response to the "new reality for our security," applauding new financing commitments from Germany and Denmark.

"President Putin's aim was to undermine NATO. What he's done is to strengthen NATO. ... He's getting more NATO on [Russia's] borders," he said.

Asked whether NATO had changed its stance on fast-tracking Ukraine's application, however, Stoltenberg said the alliance was unmoved.

"Our message to Ukraine is the same as it has been for years … it has its own right to choose its path," Stoltenberg said during a news conference.

"It's up to them whether they decide to apply to NATO," he continued, adding that the application would then be subject to a vote by member states. "It's not for Russia to try to veto such a process."

The comments come hours after Ukrainian President Volodymyr Zelenskyy addressed the U.S. Congress via videoconference, pleading for more aid to help his embattled country fight its invasion by Russia.

In a near-20 minute speech, Zelenskyy once again called on the U.S. to implement a no-fly zone over Ukraine in a bid to stem the Russian attacks, which have led to many deaths.

"Is this a lot to ask for, to create a no-fly zone over Ukraine to save people?" he said from the Ukrainian capital Kyiv. "Is this too much to ask?"

Western allies have so far been resistant to Ukraine's appeals for a no-fly zone, arguing that it would bring NATO into direct conflict with Russia — a move member states say would mark the start of a third world war.

Acknowledging that, Zelenskyy offered an alternative: the provision of additional weapons and humanitarian support alongside even tougher sanctions on Putin and his inner circle.

Russia-Ukraine talks

U.S. President Joe Biden is expected to announce hundreds of millions of dollars in additional aid to Ukraine later Wednesday and is due in Brussels next week for a meeting of NATO leaders.

Ukraine has been engaging in continued negotiations with Russia to bring an end to the conflict which has now reached its 21st day.

Earlier Wednesday, Moscow hinted that its aims would include Ukraine becoming a so-called neutral state comparable to Sweden or Austria. Under the proposals, Ukraine would be permitted its own limited army but would be prevented from its ultimate aim of joining NATO.

"The Russian Federation believes that the Swedish version of a neutral state in Ukraine can be seen as a compromise," Kremlin spokesperson Dmitry Peskov told reporters Wednesday.

Putin on Tuesday had accused Kyiv of not being serious about seeking a compromise.