An informal blockade of goods flowing out of rebel-controlled territories in the Ukrainian region of Donbas entered its third week on Feb. 21. Activists and opposition lawmakers are particularly focused on stopping shipments of anthracite coal produced in the region -- an effort aimed, at least in part, at gaining favor with nationalist voters elsewhere in Ukraine. The threat of coal shortages has alarmed the government in Kiev, which has instituted emergency measures to forestall widespread blackouts. Activists will likely agree to end the blockade before the situation reaches that point, but Donbas will remain tense as conditions for violence ripen along the front lines....