Sporadic fire fights have intensified along the front line around Nagorno-Karabakh, a mountainous enclave within Azerbaijan in the South Caucasus controlled by ethnic Armenians since a war in the early 1990s that killed about 30,000 people.
Azerbaijan has stepped up threats to take the region back and its decision to give a hero's welcome to a soldier convicted of hacking an Armenian to death on a NATO course has highlighted the risk of a war that could draw in Turkey, Russia and Iran.
When the ethnic Armenian majority in Nagorno-Karabakh declared independence as the Soviet Union collapsed, and took over more Azeri territory outside the region than within it, Christian Armenia avoided direct war with Muslim Azerbaijan.
It now says it would not stand aside if the enclave it helped establish was attacked.
Both it and Azerbaijan have more powerful weapons than two decades ago and if pipelines taking Azeri oil and gas to Europe via Turkey or Armenia's nuclear power station were threatened, war could spread.
Armenia has a collective security agreement with its regional ally Russia, while Azerbaijan has one with Turkey, itself a member of NATO for which an attack on one member state is an attack on all 28.
It makes for grim reading; Reuters has a piece on the potential for war sparking out of tensions between Armenia and Azerbaijan. The Caucasus is a volatile region, even if we don't hear about it often.
