Ukraine will not receive F-16 fighter jets from its allies this year as hoped, a spokesman for the country’s Air Force said late Wednesday, confirming that, as expected, the advanced planes won’t play a role in the current counteroffensive.

“It is already obvious that we will not be able to protect Ukraine with F-16 fighters this autumn and winter,” Yuriy Ihnat, the spokesman, told Ukrainian television. “We had high hopes for this aircraft,” he added.

Here’s what to know about Ukraine’s longstanding requests for F-16s.

First flown in 1976, the F-16 “Fighting Falcon” is a supersonic fighter jet used by militaries in 25 countries for air-to-air combat and air-to-ground strikes. It is built by the American defense contractor Lockheed Martin and manufacturers in Belgium, Denmark, the Netherlands and Norway.

The jet is widely considered to be versatile, lightweight and cost-effective — with a price tag of up to $63 million, depending on the model, according to some estimates. There are approximately 3,000 in active military service worldwide, including hundreds in the U.S. Air Force and Navy.

Ukraine has Soviet-era MiG and Sukhoi fighter jets, but has argued that F-16s could enable it to achieve air superiority, something neither side has decisively attained since Russia launched its full-scale invasion in February 2022.

Ukraine has said F-16s could beef up its air defenses, as frequent barrages of Russian missiles exhaust Kyiv’s ground-launched systems. They would also enable Kyiv’s forces to more effectively combat Russian attack helicopters targeting Ukrainian tanks and armored vehicles. Without the jets, it is also much harder for Ukraine to implement the combat tactics of NATO countries whose forces have been training the country’s military.

For months, President Volodymyr Zelensky and other senior Ukrainian officials had been calling for the United States and other countries to provide Kyiv with F-16s. But the Biden administration, which must approve any transfers of the American-made planes, had resisted.

Following a push by Britain and the Netherlands, President Biden said in May that he would allow Ukrainian pilots to be trained on the jets, a sharp reversal that moved toward letting other countries give the planes to Ukraine.

However, American officials have said that Ukraine has identified only eight combat pilots — less than a single squadron — who speak English well enough to start a period of training expected to last at least a year. About 20 others are being sent to Britain this month to learn English.

“Ukrainian pilots will return from the training, and the planes will come back with them,” Ukraine’s foreign minister, Dmytro Kuleba, said on Thursday. “Maybe they won’t arrive right in the cockpits, but it will be a synchronized process,” he said.

The counteroffensive Ukraine launched in June has yet to achieve a decisive breakthrough in the face of well-entrenched Russian defenses. And Ukrainian pilots will not be trained on the advanced aircraft in time to assist and protect the ground forces waging the campaign.

But officials in Ukraine, the United States and Europe, as well as Western defense analysts, have said in interviews that they believe Kyiv’s campaign could still prevail without the jets — though it is likely to be much more difficult.