Earlier in the week, a US media outlet reported that European countries were still waiting for an approval from the US to begin training Ukrainians on American F-16s.
"The [US] president [Joe Biden] has a given green light, and we will allow, permit, support, facilitate and in fact provide the necessary tools for Ukrainians to begin being trained on F-16s as soon as Europeans are prepared," Sullivan said.
Washington will meet "whatever timeline our European partners need" to help the pilot training program get underway, Sullivan added.
A coalition of 11 European countries, including Denmark and the Netherlands, formally agreed at the NATO summit in Vilnius, Lithuania, to train Ukrainian pilots to fly F-16 fighter aircraft.
According to media reports, the training program was expected to be launched in Denmark and Romania. NATO Secretary General Jens Stoltenberg said in June that the alliance was planning to begin the training this summer.
The Pentagon’s Joint Staff Director for Operations Lt. Gen. Douglas Sims II said on Thursday that the conditions on the battlefield in Ukraine were not "ideal" for using F-16 fighter jets given that Russia continues to possess air defense capabilities.