Why are Armenia and Azerbaijan fighting again, and why does it matter?

Several dozen Armenian soldiers and an undisclosed number of Azeris were killed on Tuesday in the deadliest fighting between Azerbaijan and Armenia since a 2020 war.

WHAT ARE ARMENIA AND AZERBAIJAN FIGHTING OVER?
 

Armenia and Azerbaijan, two former Soviet countries in the south Caucasus, have been fighting for decades over Nagorno-Karabakh, a mountainous enclave internationally recognised as part of Azerbaijan but which until 2020 was populated and fully controlled by ethnic Armenians.
 

In a six-week war that year, Azerbaijan won significant territorial gains in and around Nagorno-Karabakh. The fighting was ended by a Russian-brokered ceasefire, but skirmishes have erupted periodically since