The United States on Friday congratulated Armenia and Azerbaijan on concluding negotiations on a historic peace treaty. The US described it as an opportunity for both nations to turn the page on a decades-old conflict,

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.

Armenia and Azerbaijan have agreed on the text of a peace agreement, potentially ending over 35 years of conflict, though Azerbaijan has set several preconditions before signing.