Renewed fighting in Ukraine has in turn renewed calls to arm Ukraine, including in the United States Congress. Yet there is an enormous and largely unacknowledged flaw in the argument to provide the Kiev government with lethal weapons.

Advocates of this approach assert that sending anti-tank missiles, mortars and other arms to Ukraine will help Ukrainian forces to kill more of the Russian troops fighting alongside separatist forces in the Donetsk and Luhansk regions of eastern Ukraine. Since Russian president Vladimir Putin and other senior officials have repeatedly denied that Russian soldiers are in the country, they say, he must be trying to hide Moscow's involvement from the Russian people because he fears political opposition from soldiers' mothers (a significant political constraint during the first war in Chechnya, not to mention in Afghanistan a decade earlier) and others. If we can only kill enough of Putin's troops, they continue, Putin will no longer be able to conceal the scale of Russia's engagement in the conflict and will face public pressure to limit it or even to withdraw.

While this might appear logical on its face, this line of thinking ignores a fundamental reality of the politics of war-fighting that Americans should well understand from their own experiences: how many soldiers are dying in combat is considerably less important than why they are doing it.