Ukraine has received its first American-made F-16 fighter jets, President Volodymyr Zelensky has said.
"F-16s in Ukraine. We did it," President Zelensky said at a ceremony at an unnamed airbase, flanked by two of the planes.
Ukraine’s leader thanked allies for what they were once very hesitant to provide - though he added that many more were needed.
The arrival of the jets marks a crucial milestone in boosting the capabilities of Ukraine's air force, which largely relies on old Soviet-era jets.
More F-16s are expected and hoped in the months ahead, though Mr Zelensky admitted that Ukraine does not yet have enough trained pilots to fly them all.
He did not specify how many aircraft had arrived in Ukraine - or whether they had all been sent by Denmark, the Netherlands and the US, which he specifically thanked.
Around 65 F-16s have been pledged by Nato countries since US President Joe Biden first authorised willing European allies to send them to Ukraine in August 2023.
The F-16 was introduced in 1978. Many Western militaries are in the process of retiring the ageing fighters, replacing them with the US-made F-35, introduced in 2015.
The UK does not have any F-16s in its air force, though it is supplying long-range Storm Shadow missiles which can be fitted to the jets.
Ukraine's F-16s will work alongside a limited number of Western-supplied surface-to-air missile systems such as Patriot and Nasams which are already on the ground.
With their capacity to carry rockets, bombs and missiles, F-16s should in theory allow the air force to carry out more strikes deep inside occupied territory, and possibly on targets close to the border inside Russia.
They may also help defend against Russian glide bombs - dumb munitions fitted with pop-out wing kits and guidance modules to deliver precision strike stand-off capabilities, similar to the JDAM munitions from the United States.
Around 3,000 were dropped in March alone, mostly from Su-34 fighter-bombers.
If Ukraine can protect its F-16s on the ground, the hope is that they could play an important part in pushing back Russian aircraft to a point where they can no longer target Ukrainian ground forces with glide bombs.
Kyiv had suggested that it could keep some F-16s at foreign military bases, but that suggestion prompted President Vladimir Putin to warn that any Western bases storing Ukrainian jets would be a legitimate military target for Russia.
Experts also say the fighters could provide much needed air support to Ukrainian ground forces, who have faced relentless attacks in recent months, especially in the eastern Donbas region.
Kremlin press secretary Dmitry Peskov previously vowed that Western-made F-16s flying for Ukraine would be "shot down".
"But of course, these deliveries will not have any significant impact on the development of events on the front," he added.
