These are difficult days for Ukraine. Two years into its war against Russia, Western support for Kyiv’s fight against the Kremlin appears to be flagging. In Washington, billions of dollars in much-needed military aid have stalled in Congress. Europe has sought to fill the resulting funding gap, but officials in Brussels are quick to admit that the continent simply doesn’t have the resources to sustain Ukraine’s defense on its own. As a result, they warn, Ukraine could...