"I'm confident that they will now be in a position to be able to liberate even more land," Stoltenberg told journalists in Germany when asked if Ukraine has what it needs to successfully execute the offensive.

"One of the main issues here today has been to go through all the different capabilities, systems, supplies that the Ukrainians need to be able to retake more land," said Stoltenberg, speaking on the sidelines of a meeting of dozens of Kyiv's international supporters at the Ramstein air base.

The NATO chief also said that multiple Patriot air defence batteries had been delivered to Ukraine.

"Germany and the US have now delivered Patriot batteries, which are operational in Ukraine," he said, declining to provide exact numbers or details.

Kyiv repeatedly pushed for the high-tech system to help shield against Russian strikes, and the Pentagon said in late March that a group of 65 Ukrainian military personnel had completed training on the Patriot in the United States and returned to Europe.