The motive for the attack was not clear, but it coincided with apparently improving prospects for an agreement between Armenia and neighboring Azerbaijan on the disputed region of Nagorno-Karabakh. Armenia won control of the region, an enclave located inside Azerbaijan but populated by ethnic Armenians, and about 20 percent of Azerbaijan's territory in fighting between the two former Soviet republics that ended in 1993.

Officials in Azerbaijan immediately expressed concern that the attack could be an attempt to destabilize Armenia and throw U.S.- sponsored negotiations on the future of Nagorno-Karabakh off track. "I can't exclude that this was initiated by outside forces that want to destabilize the country during the Nagorno-Karabakh talks," First Deputy Foreign Minister Khalaf Khalov told the Reuters news service.

(Vazgen) Sarkisian was appointed prime minister last year by Kocharian, who is a former president of Nagorno-Karabakh. In the late 1980s, Sarkisian was an organizer of the nationalist movement that advocated unity between Armenia and Nagorno-Karabakh, but his more recent political campaign emphasized economic policy. Armenia has been crippled by economic isolation brought about by the dispute over Nagorno-Karabakh.