Foreign ministers from the 32 countries of the NATO defence alliance are scheduled to meet in Prague on Thursday and Friday to discuss how they coordinate military aid to Ukraine.
Ministers are expected to try to make progress in talks over a €100 billion ($108 billion) plan to transfer responsibility for combined aid from an informal, United States-led initiative to the formal structures of NATO itself. The plan was proposed by NATO Secretary-General Jens Stoltenberg in April.
At the moment, NATO itself is not officially providing any lethal aid to Ukraine's defensive war against Russia's invasion of its territory. Instead, NATO member states have been coordinating military aid through the Ukraine Contact Group (UCG), an initiative chaired by the US.
The idea behind the UCG is to help defend the position that NATO is not a party to the conflict between Russia and Ukraine.
But the UCG's reliance on US coordination has European allies worried that it could falter if November's presidential election returns Donald Trump to the White House.
There are doubts about Trump's willingness to support Ukraine in the long term, particularly after Hungarian Prime Minister Viktor Orbán, a Trump ally, said the former president "will not give a penny" to the Ukrainian war effort.
In April, Stoltenberg refused to be drawn on whether his proposal had anything to do with the possible return of Trump. He said the point is to make military aid to Ukraine more stable and predictable.
Another open question is whether weapons supplied by NATO countries should only be used to strike targets on Ukrainian territory, or whether Ukraine's forces could also use them to hit targets in Russia.
While some of Ukraine's allies fear that allowing their weapons to be used against targets in Russia would be an escalation, Ukraine argues that Russia is launching strikes on Ukraine from inside its own borders.
NATO allies are also expected to discuss air defence on their eastern flank.
Also looming over the meeting is the question of who will be the next secretary-general after Stoltenberg, who hopes to step down in July.
The candidate with the most support is the outgoing prime minister of the Netherlands, Mark Rutte, but every NATO country has a veto - a candidate needs unanimous support to get the job - and Hungary has refused to support Rutte.
Another candidate is Romanian President Klaus Iohannis.
