Reconstructing Ukraine will, by definition, be a requirement imposed by the West on Russia. Russia chose to attack Ukraine, so they pay for the damage they did AND to rebuild it. Not negotiable–period.
Pronouncements, even those supported by the UN are easy, but as demonstrated by Israel occupying territory which the UN has objected to, a status-quo in-place during a military stalemate can turn into a permanent situation despite legal arguments and, as Wendy has pointed out, there are significant reasons why the US should not take a more direct role.
Jeff