The Difficulties of Providing Kyiv with Warplanes
Ukraine's President Volodymyr Zelensky has spent much of the past week touring European capitals, pleading with leaders to send fighter jets to his country.
Ukraine was thought to have around 120 combat-capable aircraft at the start of Russia's full-scale invasion, mostly aging Soviet-era MiG-29s and Su-27s.
Officials say they need up to 200 jets to match Moscow's air power, which is estimated to be five to six times that of Kyiv.
Mr Zelensky is primarily looking for F-16s manufactured in the United States. The jet, which was first built in the 1970s, can travel at twice the speed of sound and engage targets in the air or on the ground.
Although it has been superseded by the more modern F-35, it is still widely used. According to experts, modern fighters such as the F-16 would enable Ukraine to strike behind Russian lines.
For the time being, US President Joe Biden has ruled out supplying the jets. However, countries such as Poland and the Netherlands have indicated an interest in supplying Ukraine with their own fleet.