Azerbaijan launched "local anti-terrorist activities" in Karabakh to restore constitutional order by disarming and forcing the withdrawal of Armenian military formations after six Azerbaijani citizens were killed in separate mine blasts in the breakaway region.
Baku blamed Armenian separatists for the death of the four Azerbaijani police officers and two civilians.
"Anti-terrorist operations in the region of a local character have begun," Baku's defence ministry said, adding it was using "high-precision weapons on the front line and in depth" as part of the operations.
The ex-Soviet neighbours have been locked in a decades-long dispute over the mountainous region, going to war twice in the 1990s and in 2020.
It said it was only targeting legitimate military targets using what it called high-precision weapons and not civilians or civilian infrastructure as part of what it called a drive to "restore the constitutional order of the Republic of Azerbaijan".
It said it had informed a Russian peacekeeping force in the area along with a Turkish-Russian monitoring centre which is meant to help ensure a 2020 ceasefire is upheld.
Earlier in the day, Baku said four interior ministry staff had been killed when their truck was blown up by a mine near a tunnel construction site on Tuesday. Another mine had killed two civilians, also in a truck, it said.
The blast happened "in the zone of temporary deployment of the Russian peacekeeping contingent," deployed by Moscow in 2020 as part of a ceasefire deal between Armenia and Azerbaijan.
Baku on Monday demanded Armenia to immediately withdraw its armed forces from the Azerbaijani territory of Karabakh, and abolish the military and administrative structure of the so-called regime in the region.
Karabakh, internationally recognised as part of Azerbaijan, broke from Baku's control in the early 1990s after a war. Azerbaijan recaptured swathes of land in and around it in a 2020 war.