On Thursday, White House National Security Council spokesperson John Kirby said that Ukraine would receive F-16 by the end of the year.
"If a decision were made to actually move forward on the F-16s tomorrow, it would be months and months before they were actually operational," Blinken added.
Earlier in July, Pentagon’s Joint Staff Director for Operations Lt. Gen. Douglas Sims II 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.
Ukrainian Counteroffensive 'is Tough'
Speaking about the Ukrainian counteroffensive, Blinken said that the US is estimating that it will not reach its final stage in the coming weeks and may take several months more.
"These are still relatively early days of the counteroffensive. It is tough… It will not play out over the next week or two. We're still looking, I think, at several months," Blinken told the broadcaster.
Ukraine's much-touted counteroffensive kicked off in early June after months of delays over a lack of military supplies from Western donors. The Russian Defense Ministry said Ukrainian troops kept trying but were failing to advance in the South Donetsk, Artemovsk (Bakhmut) and Zaporozhye directions. A number of Western media also noted the weak results of Kiev's counteroffensive, while Ukrainian President Volodymyr Zelensky himself admitted that progress was "slower than desired."
Russian President Vladimir Putin said on Sunday that Ukraine had lost over 26,000 soldiers since the start of the counteroffensive.