This is entirely understandable, since America's obligation to Ukraine began in 1994 when we made promises and commitments to Ukraine, then the 3rd largest nuclear power, to give up those nukes in exchange for us guaranteeing their security. (Look up the "Budapest Memorandum".) Ukraine has regretted it ever since 2014. There are still plenty of nuclear weapon scientists in Ukraine, should they decide that America's typical untrustworthiness requires building nukes again. So far, the main lesson of the Ukraine war is for nuclear states to NEVER give up their nukes, ESPECIALLY at the request of the U.S.