Ukraine has received the first of its F-16 fighter jets that could prove crucial in nullifying Russia's airstrikes on the country.

Ukrainian President Volodymyr Zelensky was in a jubilant mood on Sunday, saying: "F-16s in Ukraine. We did it."

He added: "We often heard the word 'impossible'. Now it is a reality. Reality in our skies. F-16s in Ukraine. We made it happen.

"I am proud of all our guys who are mastering these aircraft and have already started using them for our country."

Zelensky did concede one small problem – that Ukraine currently does not have enough trained pilots to fly them.

An F-16 fighter jet costs around £50million. NATO allies have promised Ukraine 65 jets to help fight back against Russia's invasion.

They could prove key in defending against Russia's deadly glide bombs. Moscow dropped 3,000 of them on Ukraine in March.

Kremlin press secretary Dmitry Peskov once warned that F-16s flying for Ukraine would be "shot down".

He said: "But of course, these deliveries will not have any significant impact on the development of events on the front."

Kyiv's troops are reportedly losing ground in the Donetsk region, but they struck a crucial blow against the Russians at sea.

Ukraine claims it sank a $300 million Russian submarine with a strike on the city of Rostov-on-Don.

Ukraine’s Ministry of Defence said: “A Russian submarine went to the bottom of the Black Sea.

“Great work, warriors. The Black Sea fish will enjoy their new home.”

H I Sutton, an independent naval analyst, said the sub was being repaired when the Ukrainians launched their attack.

He said: “The submarine was hit by Storm Shadow last year. Since then it was moved to a separate berth where it remained vulnerable to a follow-up attack. As happened this morning.

“Contrary to some reporting it hadn’t been fully repaired but this attack should close the chapter.”