Soldiers carry the coffins of fallen soldiers at Yerablur Military Cemetery in Yerevan, Armenia, on Monday. Negotiating a cease-fire is a diplomat’s nightmare. The side gaining ground doesn’t want to give up its advantage, while the defenders don’t want to make concessions at gunpoint. Therein lies the challenge for State Department officials as they try to broker a stable truce in the nasty war between Armenia and Azerbaijan. The Trump administration has tried admirably this week to mediate a settlement to this ancient battle over Nagorno-Karabakh, an enclave in the faraway Caucasus that’s within Azerbaijan’s borders but is populated by self-governing Armenians. Karabakh for three decades has been one of those “frozen conflicts,” locked in a status quo that has been favorable to Armenia and its strong ground forces. But the conflict was suddenly unfrozen Sept. 27, when Azerbaijan — using armed drones supplied by Turkey and Israel — […]