NATO eastern flank members on Friday called for a stepped-up US military presence in the region as they looked ahead to an alliance summit in Vilnius in July.

"We need to work to grow the US presence in our region on the eastern flank in terms of troops and equipment," Romania's Foreign Minister Bogdan Aurescu said after talks with his counterparts in the so-called Bucharest Nine.

Ministers from Bulgaria, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania and Slovakia reiterated calls for boosting the defence capabilities of the region which borders war-torn Ukraine.

"If we have a strong defence, then we are able to project a strong deterrence as far as Russia's destabilizing and assertive conduct is concerned," Aurescu said following the talks in a Polish city of Lodz.

"This is the only language Russia understands," he added.

Aurescu called for "more air defence, more anti missile capacities on our territories... more surveillance, reconnaissance and intelligence means."

The B9 countries also pledged further support for Ukraine in fending off Russia's invasion.

"The B9 countries are leaders here, also in terms of mobilising the allies to bolder actions, as it was in the case of transferring the MiG-29 fighter jets or tanks," Polish Foreign Minister Zbigniew Rau said.

"We all support the accession of Ukraine to NATO," Aurescu added, saying that "the priority now is to support Ukraine to win this war."

"The next month, the next period will be crucial for the fate of the war in Ukraine," Aurescu said.