ST. PETERBURG, Russia—Presidents of Armenia and Azerbaijan, Serzh Sarkisian and Ilham Aliyev during a meeting Monday mediated by their Russian counterpart Vladimir Putin agreed to increase the number observers along the border of the Nagonro-Karabakh Republic and Azerbaijan, a provision of an agreement reached last month in Vienna.

In a joint statement issued following the meeting, the presidents also agreed to hold regular tri-lateral talks.

“The Presidents stated the importance of their regular meetings for the conflict resolution and agreed to continue the meetings in the same format as a supplement to the efforts of the OSCE Minsk Group Co-chairs, who were invited to St. Petersburg to participate in the final part of the meeting,” said the statement release by the Kremlin on its official website.

The document also reiterates the two presidents’ agreement reached during a summit in Vienna on May 16 headed by Secretary of State John Kerry and with the participation of the Russian and French foreign ministers.

“They [Sarkisian, Aliyev and Putin] have agreed on increasing the number of international observers in the conflict zone. They expressed their satisfaction over the observing the ceasefire in recent weeks,” continued the joint statement.

During the summit, the three leaders exchanged ideas over the key elements of the resolution process.

Ahead of the tri-partite summit, Putin met with Sarkisian and Aliyev separately to discuss the Karabakh peace process.

In that meeting, Sarkisian told Putin that creating a mechanism to investigate ceasefire violations would lay the groundwork for productive discussions.

“Our position on the Karabakh issue is well known to everyone. We want this conflict be resolved exclusively through peaceful means. I would like to thank Russia as a co-chair of the Minsk Group for its understanding and efforts regarding this issue,” Sarkisian was quoted as telling Putin by the ITAR-TASS news agency.

“Regrettably, such conflicts are never resolved at the whim of one party. We would be happy if we managed to make progress today toward the implementation of the agreements that we have reached, in other words, to create mechanisms of investigating truce violations. This would create a good working climate for talks,” said Sarkisian.