T HE SOUTH CAUCASUS is a mosaic of warring rivals and closed borders. Lookout posts and bunkers dot its frontiers. On August 8th Donald Trump met Armenia’s prime minister, Nikol Pashinyan, and Azerbaijan’s president,

Whether this is just a photo opportunity or a lasting end to a conflict that has undermined stability in a region dominated by Russia and Iran will depend on whether the U.S. can address several key challenges.

Armenia and Azerbaijan have been at odds since the late 1980s when Nagorno-Karabakh, a mountainous Azerbaijani region mostly populated by ethnic Armenians, broke away from Azerbai