President Joe Biden recently requested another $24 billion in aid to Ukraine, including $13 billion in military aid. This adds to the estimated $113 billion, including $62 billion in security assistance, already provided by the United States since the conflict began—considerably exceeding the amount provided by European states, who presumably have a more direct interest in the outcome of the conflict than the U.S. The request comes at a difficult time for the administration. According to a CNN poll, a majority of Americans now believe the United States has already done enough to help defend Ukraine from the Russian invasion....