A US fighter aircraft F-16 performs aerobatic maneuvers on the last day of Aero India 2019 at Yelahanka air base in Bangalore, India, Feb 24, 2019. (PHOTO / AP)

MOSCOW — Russian President Vladimir Putin warned on Wednesday that if F-16 fighters given to Ukraine are used from third-party territories, they'll be legitimate targets for Russia, no matter where they are.

"If they are used from airfields of third countries, they become a legitimate target for us, no matter where they are," Putin said during a conversation with military pilots in the Tver region.

Ukraine has long been asking its partners to transfer F-16 fighters to it. However, the West emphasizes the impossibility of supplying Kiev with such aircraft without proper preliminary training of pilots and ground service personnel. Denmark, the Netherlands, the United States and several other Western countries are currently actively involved in training Ukrainian pilots.

However, Kyiv's partners note that the importance of the F-16 should not be overestimated. North Atlantic Treaty Organization Secretary General Jens Stoltenberg said these fighters alone will not be able to fundamentally change the situation in the combat zone, although they will partially strengthen the capabilities of the Ukrainian troops.

Separately, the Russian Foreign Ministry said on Thursday NATO's activities in Eastern Europe and the Black Sea region are focused on preparing its allies for a potential confrontation with Russia, citing militarization activities in the region.

Romanian authorities have previously announced their readiness to invest 2.5 billion euros ($2.7 billion) in the modernization of the Mihail Kogalniceanu air base in Constanta County. The base is set to expand into a military town capable of accommodating the families of 10,000 military personnel, with plans to create urban infrastructure, said the ministry.

Construction has begun in the southern part of the future military town, where access roads and a robust power grid are currently being built. The modernization of the air base could make it the largest NATO base in Europe by 2040. The US military has been using this base since 1999, it said.

"The expansion of the Romanian air base is yet another proof that the North Atlantic bloc continues its unrestrained militarization of Eastern Europe and the Black Sea region," said the Russian Foreign Ministry.

The ministry added that "the forced enhancement of coalition capabilities is also taking place in Poland and the Baltics."

"Such activity by NATO members is provocative, exacerbates military tension along our borders, and creates additional security threats to Russia. All this is aimed at preparing the bloc's allies for a potential collision with our country," the ministry said.

"We will monitor the developments in Romania, assess the emerging risks, and take them into account during military planning," the ministry added.