PRAGUE -- After the May 7 meeting of the presidents of Azerbaijan and Armenia in Prague, Matthew Bryza, one of three co-chairs of the OSCE's Minsk Group, called it "the most substantive exchange of views between the presidents so far."
The Minsk Group oversees negotiations on the Nagorno-Karabakh frozen conflict.
In an interview with RFE/RL's Azerbaijani Service, Bryza, who is also U.S. deputy assistant secretary of state for European and Eurasian affairs, said there was a "conceptual breakthrough."
"You have to have conceptual breakthroughs and then technical breakthroughs. So, conceptually I would say, we pretty much had that today. Now we have to create the technical breakthroughs," Bryza said.
Bryza dismissed speculation that competing interests between Russia and the United States were influencing the negotiations.
"Russia is constructive when it comes to the Nagorno-Karabakh peace process. My colleague and friend Yury Mikolajewitsch Merzlyakov [the Russian co-chair of the Minsk Group] has never been anything but constructive, and I can say the same about his Deputy Foreign Minister [Grigory] Karasin and Foreign Minister [Sergei] Lavrov," Bryza said.
"As difficult as our relations are with Russia with regard to Georgia, they are equally positive with regard to Nagorno-Karabakh."
Bryza also said that the details to solve the conflict can be finalized in working with the foreign ministers of the two countries.
Nagorno-Karabakh has been under the control of ethnic-Armenian forces since a six-year conflict killed about 30,000 people and displaced another million before a truce was reached in 1994.