Today, Azerbaijan has more modern types of arms, said Armenia`s President Serzh Sargsyan at a joint press conference with the German Chancellor Angela Merkel on April 6.

"These three days of hostilities showed that these arms are effective," said Sargsyan, Interfax reported.

"Russia is our strategic ally; we are in one security system [Collective Security Treaty Organization]," he noted, adding, "Naturally, we are sensitive that Russia and not only Russia, but also the countries of this structure are selling weapons to Azerbaijan."

The conflict between the two South Caucasus countries began in 1988 when Armenia made territorial claims against Azerbaijan. As a result of the ensuing war, in 1992 Armenian armed forces occupied 20 percent of Azerbaijan, including the Nagorno-Karabakh region and seven surrounding districts.

The 1994 ceasefire agreement was followed by peace negotiations. Armenia has not yet implemented four UN Security Council resolutions on withdrawal of its armed forces from the Nagorno-Karabakh and the surrounding districts.

On the night of April 2, 2016, all the frontier positions of Azerbaijan were subjected to heavy fire from the Armenian side, which used large-caliber weapons, mortars and grenade launchers.

The armed clashes resulted in deaths and injuries among the Azerbaijani population. Azerbaijan responded with a counter-attack, which led to liberation of several strategic heights and settlements.