KYIV, Ukraine — The F-16 fighter jets that Ukraine has received from its Western partners to help fight Russia’s invasion — one of which crashed this week while countering a Russian barrage — have been the front-line combat planes of choice for the NATO alliance for 50 years.

At least six of the warplanes are believed to have been delivered to Ukraine from European countries, and one of them crashed Monday, the Ukrainian military said, in the first reported loss of one of the planes. U.S. experts have joined a Ukrainian investigation into why it went down, military officials said Friday.

The F-16s enhance Ukraine’s military strength, especially by upgrading its air defenses and enabling it to hit distant targets with sophisticated NATO weaponry, if Western suppliers give permission for that. Analysts say the F-16s won’t turn the tide of the war on their own.

The U.S. won’t be providing any of its own F-16s. Belgium, Denmark, the Netherlands and Norway have committed to providing Ukraine with more than 60 of them over coming months in what could be a slow trickle of deliveries.

Here’s what to know:

What Can F-16s Bring to the Ukrainian War Effort?

The F-16s will likely have three core missions, says Federico Borsari of the Center for European Policy Analysis in Washington.

They will seek to intercept Russian missiles and drones that have relentlessly bombarded Ukraine; suppress enemy air defense systems; and strike Russian troop positions and ammunition depots with air-to-ground missiles.

“They will be able to affect some of the dynamics (of the war),” Borsari says.

A lot of information about the F-16 deployment is classified, including what Western governments allow them to hit and what weapons they will send with the aircraft.

The F-16s could carry United Kingdom-supplied Storm Shadow air-launched cruise missiles with a range of more than 250 kilometers (155 miles), potentially striking targets inside Russia. They might also get long-range air-to-air missiles that would threaten Russian bombers and fighter jets. The plane’s advanced radars will allow Ukrainian pilots to pinpoint targets further away than they can in their MiG-29s, Su-27s and Su-24s.

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Commanding the skies is an essential part of a war’s ground campaign, as planes offer air cover to troops. But supporting Ukrainian troop movements on the front line with ground attacks may be too risky for the F-16s, given Russia’s sophisticated air defense systems.

At the very least, the fighter jets could have a psychological effect on Russian pilots, and offer a morale boost for Ukrainians toiling against the Kremlin’s forces.

What Are the Challenges for Ukraine?

Marina Miron of the Defense Studies Department at King’s College London ticks off a long list of challenges the F-16s bring for Ukraine.

The roughly nine-month training in the U.S. and Europe for Ukrainian pilots amounted to a crash course compared with the usual three-year course for Western pilots in what Miron calls “a very complex piece of machinery.” That will mean limitations on their performance.

The F-16s also require a large number of support personnel, such as skilled maintenance engineers, munitions loaders, intelligence analysts and emergency crews.

Ukraine must also establish a network of radar stations, reinforced hangars, a supply of spare parts and refueling systems. Quality airfields are also a must as the F-16 air intake is close to the tarmac and runs the danger of sucking debris and dirt into the engine.

“So many associated issues need to be sorted out,” Miron says.

Ukrainian pilots with no combat experience in F-16s may shy away from engaging in dogfights.

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How Has Russia Reacted?

Kremlin spokesperson Dmitry Peskov said Russian authorities have offered rewards to servicemen who destroy F-16s, which would have propaganda value for the Kremlin.

The Ukrainian F-16s are up against Russia’s formidable S-300 and S-400 mobile surface-to-air missile systems that can target multiple aircraft at a time. Russia’s military also has what are estimated to be several hundred operational fighter jets, as well as sophisticated air surveillance radars.

Russia’s Su-35 fighter jet is one of the biggest threats to the F-16, Borsari of CEPA says. It has a long-range radar that allows it to track and engage up to eight targets at a time across a wide area.

The Kremlin’s forces may also try to destroy the F-16s on the ground with long-range missiles. They have already targeted Ukraine’s limited number of suitable airfields.

The Ukrainians need to park the F-16s in hardened hangars, disperse them between various locations, station decoy model aircraft and be ready to take off quickly in the event of an air raid warning, analysts say.

How Will Ukraine Protect the F-16s?

Although Russian forces will try to strike the F-16s at the airbases where they are kept, Ukraine has robust defenses to protect the fighter jets against such attacks, says Ukrainian aviation expert Anatolii Khrapchynskyi.

Ukraine has capabilities “to protect its airfields with anti-aircraft defenses to deflect (Russian) attacks,” Khrapchynskyi told The Associated Press. “During the entire time since Russia has invaded Ukraine, it has been actively trying to hit Ukrainian airfields, but they have been somewhat unsuccessful.”

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Khrapchynskyi said the F-16s will significantly increase the capabilities of the Ukrainian Air Force to protect the country’s air space from Russian attacks and increase the range that Ukraine can strike strategic targets in Russia.

“With the acquisition of F-16 aircraft, we will be able to solve a number of problems that are currently hurting Ukraine. These include: Russia’s massive missile attacks, its use of guided aerial bombs, and the deployment of S-300 installations in the border regions of Sumy and Kharkiv,” says Khrapchynskyi.