The German and British foreign ministers are urging Serbia and Kosovo to resolve their differences through diplomacy and not risk wasting a “crucial opportunity for progress.”

Guido Westerwelle and William Hague wrote in Germany’s Frankfurter Allgemeine Zeitung that the two must find a solution which “respects Kosovo’s borders” and moves both Serbia and Kosovo toward EU membership.

They add in the newspaper’s Monday edition: “If they do not, they will be throwing away a crucial opportunity for progress, at the expense of their citizens’ interests.”