The request will be made next Thursday ​at a meeting of the Ukraine Defence Contact ​Group, an alliance of more than 50 ⁠countries also known as the Ramstein group, where ​allies organise financial and military aid for Kyiv.

“We have ​a six- to nine-month window of opportunity on the battlefield that requires an urgent acceleration of funding,” the source ​said.

Russia’s advances on the battlefield have slowed this ​year - effectively grinding to a halt last month - as Ukrainian mid-range ‌drone ⁠strikes have harmed its supplies and logistics for the front line.

Ukraine’s long-range drone strikes, meanwhile, are inflicting pain on Russia’s energy sector.

Putin last week ​said that ​Russian forces ⁠were still advancing on the battlefield every day and there was no risk to ​Russia’s economy, though he acknowledged Ukrainian ​strikes were causing ⁠harm.

Some allies will each be asked to contribute between $2 billion and $6 billion to reach the $20 billion target, ⁠either ​in the form of aid ​or a loan, the source said.

The request was first reported ​by Politico.