Washington received assurances from Kiev that the Western-supplied F-16 fighter jets will not be used to carry out strikes on Russian soil, White House National Security Council Spokesperson John Kirby said on Wednesday.

"We have gotten that assurance at various levels, not just from [Ukrainian] President Zelenskyy but from other senior military and defense leaders in Ukraine," Kirby told reporters when asked about the matter.

"We certainly don't want to see attacks inside Russia that are being propagated, that are being conducted using US-supplied equipment," he added, stressing that the US policy against these strikes will remain unchanged.

Read more: West's F-16s may be no match to Russia's missiles: Bloomberg

“We don't want to see US-supplied equipment used to strike inside Russia, we don't support attacks inside Russia, and we are not going to change our policy about not enabling or encouraging those attacks,” the official said.

Washington opposes Ukrainian attacks on Russian territory to "avoid World War Three," he added.

He further emphasized the importance of not dragging this war beyond the borders of Ukraine, warning that this would affect the security of the US, EU, and Russia alike.

"I think we can all agree that a war that escalates beyond that – that actually does suck in the West and NATO and the United States – is not only not good for our national security interests, it’s not good for the Ukrainian people, it’s not good for the people across Europe, it’s certainly not good for the Russian people."

Earlier this month, the White House greenlighted the decision for itself and its Western partners to supply Kiev with US-made F16 jets, but that decision has been met with some reluctance from Germany and Portugal's part. Though the two countries said they would not supply the aircraft to Kiev, they said they would assist Ukrainian troops through other means.

Washington stressed that the deliveries of F-16s are planned for the long term, not for Kiev's immediate operations. 

Moscow slammed the decision and said the delivery of the fighter jets was another stage of escalation and warned that the warplanes will become a legitimate target for Russian forces. 

Last Sunday, Ukrainian Defense Minister Oleksii Reznikov said that pilots for training on F-16 fighters have been selected, adding that the training is due to start once everything is "technologically" prepared.

Reznikov revealed recently that Ukraine requires 48 F-16 fighters in order to take back the annexed territories. When asked to comment about the number of warplanes and the terms of their delivery to Ukraine, the official refused to comment.