After US President G7 Summit announced on Friday that Ukraine would receive F-16s, Washington has noted that Ukrainian pilots will be trained in the use of F-16 fighter jets.
On Saturday, Russian Deputy Foreign Minister Alexander Grushko was quoted by the TASS news agency as saying that there are "colossal risks" for Russia's allies to supply F-16s to Ukraine.
White House national security adviser Jake Sullivan said that as the conflict evolves, so will the weapons support to Ukraine.
"As the training unfolds in the coming months, we will work with our allies to determine when plans will be delivered, who will be delivering them, and how many," Sullivan said.
The UK would work with the Netherlands, Belgium and Denmark "to get Ukraine the combat air capability it needs," said UK Prime Minister Rishi Sunak, although Sullivan did not say which countries would provide support.
The Danish defense ministry said it would support the training process.
According to Sullivan, the training of Ukrainian pilots is scheduled to begin next week.