NATO Secretary General Jens Stoltenberg ruled out creating a no-fly zone over Ukraine on Friday despite Kiev's repeated requests for an aircraft ban amid heavy Russian bombing.
"Allies agree that we should not have NATO planes operating over Ukrainian airspace or NATO troops on Ukrainian territory," Stoltenberg said in a Brussels press conference.
"We have a responsibility as NATO allies to prevent this war from escalating beyond Ukraine, because that would be even more dangerous, more devastating, and would cause even more human suffering," he added.
NATO would not be able to enforce a no-fly zone, a region of airspace where certain aircraft are not permitted to fly, without shooting down Russian planes, Stoltenberg said.
He added it was the alliance's view this could result in a "full-fledged war in Europe involving many more countries."
Ukrainian President Volodymyr Zelensky has called repeatedly for NATO to establish a no-fly zone as Russian artillery bombing and airstrikes pummel cities in his country.
The foreign ministers of the 30 NATO countries - most of them also members of the European Union - gathered for a meeting with US Secretary of State Antony Blinken at the alliance's headquarters in Brussels.
Ministers were meeting as Russian President Vladimir Putin's invasion of Ukraine entered its ninth day. Concerns about civilian casualties are mounting, with more than 1 million people already having fled, according to the United Nations Refugee Agency.
Conflict to worsen
Stoltenberg also warned the conflict was set to worsen, "with more death, more suffering, and more destruction as Russian armed forces bring in heavier weaponry and continue their attacks across the country."
The alliance chief said NATO had also seen reports of Russia using weapons in Ukraine that violate international law including outlawed cluster bombs.
NATO has also started consultations on a wide-ranging build-up of forces on the alliance's eastern flank as a result of Russia's invasion of Ukraine, Stoltenberg said. More details are expected later in March.
"We are now seriously considering a significant increase of that presence - with more troops, with more air defence, with deterrence, by defence," Stoltenberg said.
Foreign ministers warned against a NATO intervention in the conflict, with Luxembourg's Foreign Minister Jean Asselborn saying that this could lead to a global catastrophe.
Czech Foreign Minister Jan Lipavský also warned before the meeting that attempts to impose a no-fly zone would make NATO a party in the conflict.
Finland's Foreign Minister Pekka Haavisto said the risk to civilians in Ukrainian cities was a major concern, but did not comment on calls to establish the aircraft ban.
Nuclear plant in Ukraine
The head of the NATO military alliance repeated his condemnation of Moscow's attack on the Zaporizhzhia nuclear power plant in Ukraine, declaring it an example of Russian "recklessness" in the conflict.
Stoltenberg said the attack "demonstrates the recklessness of this war ... and the importance of Russia withdrawing all its troops and engaging in good faith in diplomatic efforts."
The UN Security Council should impose safe zones to prevent fighting near nuclear plants in Ukraine, Lithuania's foreign minister Gabrielius Landsbergis wrote on Twitter.
Humanitarian corridors to allow people to flee the conflict should also be established, he added. Landsbergis also said before the NATO meeting the no-fly zones debate should happen at the UN.
EU foreign ministers later slammed Russian attacks on civilians in Ukraine at a special meeting of EU foreign ministers on Friday attended by Blinken and Stoltenberg.
"These are war crimes," Irish Foreign Minister Simon Coveney said ahead of the meeting.
Putin's "war of aggression" on Ukraine, aims to act with the "most brutal severity" against civilians, German Foreign Minister Annalena Baerbock said.
The EU's top diplomat Josep Borrell said Russia was "bombing and shelling everything, hospitals, houses, schools." This was a barbaric way to conduct war, he said.
"The humanitarian situation on the ground is getting more and more difficult," Borrell later said at a press conference. "It looks like they want to destroy Ukraine," he added.
Ukrainian Foreign Minister Dmytro Kuleba joined the ministers via video link. British Foreign Minister Liz Truss and her Canadian counterpart, Mélanie Joly, also took part.
Discussions centred on the bloc's response to Putin's invasion of Ukraine as well as the coordination needed to implement the massive sanctions recently adopted.
Some EU member states are pushing to take further action on Russia with sanctions, according to an EU diplomat.
Baerbock said earlier at the NATO meeting further sanctions were under way to "specifically target Putin's centre of power." Baerbock later said it was important to effectively introduce sanctions already adopted.
Questioned about possible sanctions on the Russian oil and gas sector, Borrell said "everything remains on the table."
Massive EU sanctions on Russia for invading Ukraine were possible due to close cooperation with the United States, European Commission President Ursula von der Leyen said.
The EU had taken "historic" action to respond to Russia's invasion, Blinken said. "Things that none of thought possible weeks ago, now are reality," he said.