Armenia and Azerbaijan were locked in conflict over Nagorno-Karabakh for nearly four decades after the Soviet Union they were both members of collapsed.

But hurdles remain. Azerbaijan also said Armenia’s constitution must “eliminate the claims against the sovereignty and territorial integrity of Azerbaijan,” as a prerequisite to allow for the signing of the peace treaty.

Representatives of Armenia and Azerbaijan have concluded negotiations and agreed on the text of a peace agreement, the foreign ministries of both countries announced.