On several consecutive mornings in early 2014, I woke up with one agonizing plea: Please, Lord, let the Ukrainian service members still be alive. I feared that while I slept, Russians might have slaughtered thousands of outgunned and outnumbered Ukrainians trapped on their own air and naval bases.

Hostilities between Russia and Ukraine began in that year with Russia’s lightning-quick occupation of Crimea, a region coveted by Russian President Vladimir Putin. Within hours, Ukrainian service members at various military installations were trapped on their own soil by Russian forces. If they had fought back, almost certainly they would have died. If they didn’t resist, it was unclear how they would fare. My job, as deputy assistant secretary of defense, was to lead a team drafting proposals for then-Defense Secretary Chuck Hagel and President Barack Obama, outlining options for the United States to help Ukraine defend itself against further Russian aggression.