Britain and the Netherlands are working on an "international coalition" to help Ukraine procure F-16 fighter jets that Kyiv says are vital to its defense as Russia ramps up its its aerial strikes, a spokesperson for UK Prime Minister Rishi Sunak said Tuesday.

The two NATO allies are trying to get the US-made warplanes to Ukraine as well as training Kyiv's pilots to fly them, according to the Downing Street readout following a meeting between Sunak and Dutch Prime Minister Mark Rutte at the Council of Europe Summit in Iceland.

Ukraine, which has been saying the fighter jets are essential to defend against Russian missile and drone attacks, welcomed the announcement from the British and Dutch leaders.

"We need F-16s, and I am grateful to our allies for their decision to work in this direction, including training our pilots," said Andriy Yermak, head of the office of President Volodymyr Zelensky.

Yermak said Belgium, another NATO ally, in particular, had "confirmed its readiness to train" Ukrainian pilots.

Britain does not have F-16s in its air force, but the Netherlands and Belgium do. The US Air Force has almost 800 F-16s in its fleet.

Speaking in the United Kingdom Monday, Zelensky welcomed promises of fresh military aid from European leaders -- but renewed his demands to be provided with modern fighter jets.

Following a visit with Sunak, Zelensky hinted that Ukraine is closer to receiving F-16s, saying that Kyiv and London were "actively moving forward" on a plan. Zelensky also thanked the UK for agreeing to train Ukrainian pilots.

The US Air Force calls the F-16, which first flew in 1978, a "relatively low-cost, high-performance weapon system."

The single-engine jets can act in air-to-air or ground-attack modes, flying in all weather conditions with a range of 500 miles (860 kilometers).

It would be a substantial upgrade to the aircraft in Ukraine's fleet now, largely Soviet-era warplanes that were either in Ukraine's air force before the Russian invasion or have been given to Kyiv by other European states like Poland that used to be in the Soviet orbit.

Despite Zelensky's repeated pleas for F-16s, many of Ukraine's allies have been reluctant to supply Kyiv with weapons that can reach Russian soil.

Early on in the war, the US believed that supplying Ukraine with new fighter jets would risk an escalation between NATO and Russia.

Meanwhile, US and allied officials have previously said the jets would be impractical because they require considerable training and Russia has extensive anti-aircraft systems that could easily shoot them down.

Any movement of F-16s to Ukraine would require US approval and US President Joe Biden said earlier this year that Kyiv did not need the fighter jets.

But CNN reported in March that the US is working with Ukrainian pilots in the United States to determine how long it would take to train them to fly F-16s, according to sources briefed on the matter.