WASHINGTON — For a moment last week, war seemed imminent. A day after Russia’s foreign minister, Sergey V. Lavrov, warned Ukraine’s leaders against using force in the crisis there, the Ukrainian military attacked a checkpoint outside the separatist-held town of Slovyansk. Russian forces across the border responded with maneuvers labeled “exercises,” coupled with statements from the Kremlin that amounted to “you were warned.” Russian television made Slovyansk look like Guernica; Ukrainian news media reported that separatist militants were using kindergartners as human shields.

As each side revved up its propaganda, the world got another taste of the confusion, uncertainty and distortion of information that have brought this conflict to the brink. An absence of legitimate authority in eastern Ukraine has left an absence of transparent, agreed-upon facts — a breeding ground for suspicion and manipulative diplomatic games on the margins of the truth that may yet carry the region to war.

Consider the armed “green men” who seize towns and whose photos circulated in the media this month. Do they work for the Russians? The United States has said Russian culpability is beyond “a shadow of a doubt.” The Russians have issued categorical denials. The Ukrainian government’s photo evidence of involvement of Russian special forces has been undermined by apparent errors of location and misidentification, but not before the images were submitted to the Organization for Security and Cooperation in Europe, endorsed by the United States State Department and headlined in American news media.

Doubt’s shadow has not left Ukraine. Instead, the failure to agree on facts — to share a basic reality — has become the norm. Who distributed leaflets ordering Jews to register with authorities? Was it the anti-Semitic new “government” of the self-proclaimed Donetsk Republic, as the Ukrainian government claims, or was it a provocation designed to discredit the pro-Russian separatists? And who killed three men at a checkpoint in Slovyansk last week, Russian military intelligence or Ukrainian nationalists?