According to the NYT, Ukraine can rely on the Netherlands, Denmark, Belgium, and Norway. In particular, the Netherlands is one of four European countries that have quietly signaled that they are ready to send F-16s to Kyiv. According to British analysts, their fleet, together with those of Denmark and Belgium, could provide at least 125 combat-ready F-16s.
A Ukrainian official said that Norway, which retired an unspecified number of F-16s last year in favor of the more advanced F-35 Joint Strike Fighter, is also ready to contribute. However, Kyiv is asking, at least for now, for only 24 to 36 planes.
So far, no European government has officially requested the US for permission to send fighter jets to Ukraine.