The Ukrainian leader announced the F-16's entry into service while meeting military pilots at an air base.

At a location that the Ukrainian government requested not be disclosed for security reasons, Mr. Zelenskiy said: "F-16s have begun to be used in Ukraine. We have succeeded. I am very proud that people continue to train to master this aircraft and have begun to use them for our country."

The top commander in the Ukrainian military, Oleksandr Syrskyi, thanked the Ukrainian president and other officials for working “24/7” to secure the planes. He said their operation would save the lives of Ukrainian soldiers.

The deployment of these fighter jets is a major milestone for Ukraine, but it remains unclear how many aircraft will be deployed and what impact they will have on air defense and on the battlefield.

Russia has identified several bases that could host these planes and has pledged to shoot them down.

Manufactured by Lockheed Martin, the F-16 has long been coveted by Ukraine for its combat capabilities and global availability. It is equipped with a 20mm rotary machine gun and can be armed with bombs and missiles.

"A new phase"

Speaking to reporters on the tarmac of an airport, Mr. Zelenskiy said that Ukraine still does not have enough trained pilots to use the F-16.

“The positive thing is that we still expect to receive more F-16s… and more personnel are still being trained,” he said.

It is important that allies come up with ways to expand training and opportunities for both Ukrainian pilots and engineering teams, he said.

Ukraine has long relied on a fleet of Soviet-era aircraft that are outnumbered by a much larger and more modern Russian fleet.

Russia has used this advantage to launch long-range missile strikes against targets across Ukraine and pound Ukrainian positions on the front line with thousands of guided bombs, supporting its forces as they slowly advance across the battlefield in eastern Ukraine.

"This is a new stage in the development of the air force of the Armed Forces of Ukraine," Zelenskiy said.

It is not yet clear what type of missile the planes will be armed with. Military analysts say a longer-range missile would give them a greater impact on the battlefield.

Mr. Zelenskiy also said he hopes to lobby neighboring allied countries to help intercept Russian missiles aimed at Ukraine with discussions through the Ukraine-NATO Commission.

"This is another tool that I would like to try to leverage, so that NATO countries can discuss with Ukraine the possibility of a small coalition of neighboring countries being able to shoot down the missile."

Nguyen Quang Minh (Briefly translated from Reuters)