President Trump’s visit this week to the Army’s sole surviving tank plant in Lima, Ohio is the first such presidential visit there since George W. Bush stopped by in 2003. President Obama never visited, and the depressed level of military spending during his presidency nearly shut the place down. Wrongly assuming that Russia had ceased to be a threat to global security, the Obama administration cut the number of Army armored brigades to a record low of nine. Production of upgraded Abrams tanks at the Lima site fell to a single tank per month, and the Army seriously considered mothballing...