US President Donald Trump has offered to give Ukraine the right to produce Patriot interceptor missiles, which could help Kyiv defend against Russia's ballistic missile attacks.

"We are gonna give you a licence to make Patriots," Trump told Ukraine's Volodymyr Zelensky during Wednesday's Nato summit in Ankara. "I think they can produce them very quickly once we explain it."

He said he had not yet informed defence manufacturers Lockheed Martin and Raytheon of his decision, "but that'll work out alright".

Patriots detect and intercept missiles and are regarded as one of the world's best air defence systems - and the most expensive: a single battery, with missiles, is worth around $1bn (£740m).

It also has lengthy production times, with only 600 missiles produced per year, according to the US Department of Defence.

The US is reluctant to part with any, given that it used more than half of its stockpile during its war with Iran earlier this year, according to the US-based think tank Center for Strategic and International Studies (CSIS).

"We have Patriots, but we don't have that many. We need them for ourselves too," Trump said.

Yet Ukraine needs them urgently. In recent months Moscow has increased its ballistic missile strikes on Ukraine, causing dozens of deaths in Kyiv alone over the course of the last week.

In late May, Zelensky confirmed Ukraine had formally asked the US to authorise licensed production of Patriots.

After four-and-a-half years of war the fighting on the front line has mostly stalled, the Black Sea is at a standstill, and Ukraine has by and large learned to counter the hundreds of drones Russia fires at it on a nightly basis.

But ballistic missiles - which Zelensky called Russia's "last major advantage" - travel at high velocity and a steep path which makes them difficult to stop.

Many manage to pierce through Ukraine's depleted air defences.

Earlier this week the Ukraine Air Force said a "serious shortage" of interceptor missiles meant none of the 23 ballistic missiles fired by Russia on Sunday night were shot down. More than 20 people died in that attack.

Trump said the US would give Kyiv the licence to produce Patriots so that it couldn't "complain that we're not giving them enough".

In Kyiv, there was some degree of scepticism that the interceptor missiles could be produced on Ukrainian territory at this stage.

Military expert Ivan Stupak, an ex-security service officer, told the BBC that while the Patriots were vital for Ukraine's defence: "Unfortunately, Ukraine is not able to produce such kinds of advanced munition, because it's really sophisticated, cutting-edge equipment."

"Technically and legally, I think this will be deployed to European soil instead - and supervised," he added, and could take many months.

During the news conference, Trump acknowledged that Ukraine had been recently having significant success in launching long-range strikes on Russia, which have hit targets thousands of kilometres away from the frontline.

"It's an escalation, but it's also an escalation that can help lead to an end," Trump said.

Sitting next to Trump, US Secretary of State Marco Rubio said Ukraine's strikes on Russian refineries were needed to show Moscow "how difficult it is to defend its airspace", and thus push the Kremlin to end the war.

In his remarks Trump also claimed Vladimir Putin - with whom he said he spoke often - wanted to make a deal to end the war with Ukraine, which began with Russia's full-scale invasion of the country in 2022.

The US president has made similar comments before, but to this day his efforts to broker talks between Kyiv and Moscow have not yielded any results.

Not for the first time, Trump brought up the possibility of Zelensky and Putin meeting to discuss ending the conflict.

Putin has repeatedly said he would be open to such a meeting but only if it was held in Moscow. Although many have interpreted the invite as a provocation - the Kremlin knows Zelensky is extremely unlikely to ever agree to travel to Russia - Trump on Wednesday asked the Ukrainian president if he was prepared to go to the Russian capital.

"It's difficult - there are a lot of Ukrianian drones there," Zelensky quipped, alluding to Ukraine's long-range drone strikes on Moscow.