President Recep Tayyip Erdoğan, Russian counterpart Vladimir Putin discussed on Tuesday the Azerbaijan - Armenia conflict in occupied Nagorno-Karabakh and developments in Syria in a phone call.

Nagorno-Karabakh is an Azerbaijani territory that has been under the control of Armenian forces since a war there ended in 1994.

The current fighting that started Sept. 27 marks the worst escalation in the conflict since the war’s end.

After two failed attempts by Russia to broker a truce, the U.S. waded onto the scene on Friday, with Pompeo hosting the Armenian and Azerbaijani foreign ministers for separate talks.

“Both must implement a cease-fire and return to substantive negotiations,” Pompeo said in a tweet after the negotiations and the two sides announced that they reaffirmed commitment to a cease-fire that would start at 8 a.m. on Monday.

However, shortly after the cease-fire came into effect, Armenia continued to attack Azerbaijan, according to Azerbaijani officials.

Following the attack, Turkish Foreign Ministry released a statement, condemning the move.

The Foreign Ministry also pointed at the fact that although Armenia has been violating the cease-fire for the third time, none of the Minsk Group countries have made a statement to condemn its actions.

The Organization for Security and Co-operation in Europe (OSCE) Minsk Group – co-chaired by France, Russia, and the U.S. – was formed in 1992 to find a peaceful solution to the conflict but to no avail. A cease-fire, however, was agreed to in 1994.