The US is at or very near the end of its capacity to give, while fears grow of a military confrontation with Russia. Defense Secretary Lloyd Austin signaled this week that the U.S. and its Western allies are having trouble keeping pace with Ukraine’s demand for the advanced weaponry it needs to fend off Russia’s invasion. That signal reflects dwindling supplies for Ukraine and fear in the White House of escalation that could lead to war between the U.S. and Russia. The risk of reduced U.S. stockpiles of high-end munitions has been reported almost since the U.S. began contributing to...