US President Joe Biden said on Monday that he would not send F-16 fighter jets to Ukraine to help its defence against Russia's invasion, which is nearing its one-year mark.
"No," he said when asked by reporters at the White House if he was in favour of sending the jets.
After the US and western nations agreed to send military tanks to Ukraine following lengthy talks and serious divisions, Ukraine's leaders have begun placing F-16 fighter jets at the top of latest weapons wish list.
Ukraine is also saying that pilots would need six months to learn how to fly them.
The upgrade in support sparked hope in Kyiv that it would soon be getting F-16 warplanes to bolster its depleted air force, but the issue remains very much under debate in the West.
Politico reported that several US military officials support sending F-16s, while the White House is wary.
With the first anniversary of Russia's invasion on February 24 looming, there are growing expectations that Mr Biden could travel to Europe as a show of support for the alliance supporting Ukraine.
Poland is at the heart of the effort as a logistics centre, provider of weapons and key US ally in eastern Europe.
"I'm going to be going to Poland. I don't know when, though," Mr Biden told reporters when asked about a visit.
Agence France-Presse contributed to this report
