Serzh Sargsyan decided not to attend the NATO summit in Lisbon because "a draft summit declaration has retained the previous generalized position on the resolution of conflicts in the South Caucasus", RIA Novosti reported.
"The Armenian side has many times stressed that the general wordings on conflict resolution are unacceptable," he said.
Sargsyan was apparently referring to the Nagorny Karabakh conflict between his country and Azerbaijan.
The conflict between the two South Caucasus countries began in 1988 when Armenia made territorial claims against Azerbaijan. Armenian armed forces have occupied 20 percent of Azerbaijan since 1992, including the Nagorno-Karabakh region and seven surrounding districts. Azerbaijan and Armenia signed a ceasefire agreement in 1994.
The co-chairs of the OSCE Minsk Group - Russia, France, and the United States - are currently holding negotiations to resolve the dispute.
Armenia has failed to implement U.N. Security Council resolutions stipulating the liberation of Nagorno-Karabakh and surrounding regions.