NATO chief Jens Stoltenberg on Tuesday said Russian President Vladimir Putin had "shattered peace in Europe" by invading Ukraine, adding that the Western defence alliance would defend "every inch of our territory".
He spoke during a visit to the Lask airbase in NATO member Poland, whose neighbour Ukraine has been fighting back against a Russian offensive that is now in its sixth day.
"President Putin has shattered peace in Europe. Allies condemn the unjustified and brutal invasion of Ukraine," Stoltenberg told reporters alongside Polish President Andrzej Duda.
"The Russian assault is totally unacceptable, and it is enabled by Belarus. NATO allies provide support to Ukraine," he said.
In a separate press conference in Poland, French Foreign Minister Jean-Yves Le Drian said "sanctions should also apply to Belarus" as it is "a state in the pocket" of Russia.
He spoke in the central city of Lodz alongside his German counterpart as well as Polish Foreign Minister Zbigniew Rau, who said "Belarus is just as responsible as Russia for the aggression".
"Were the war to persist, the scope of sanctions would expand. We have an agreement on the matter," Rau told reporters.
All three heads of diplomacy also said the EU would contribute to rebuilding Ukraine after the war.
Stoltenberg stressed that as a defensive alliance, "we do not seek conflict with Russia", but said it was prepared to defend itself and had recently beefed up its eastern flank.
"Our commitment to article 5, our collective defence clause, is iron-clad. We will protect and defend every inch of NATO territory," he said.
"Russia must immediately stop the war, pull out all its forces from Ukraine, and engage in good faith in diplomatic efforts. The world stands with Ukraine in calling for peace."
He said NATO allies are backing Ukraine with military and financial support as well as humanitarian aid, but that the alliance would not send soldiers.
"NATO is not going to be part of the conflict. So NATO is not going to send troops into Ukraine or move planes into Ukrainian airspace," Stoltenberg added.
The NATO chief also thanked Poland for so far taking in over 200,000 Ukrainian refugees.