April 8 (UPI) -- Russian President Vladimir Putin met with Turkish President Recep Tayyip Erdogan in Moscow Monday, where the two expressed a desire to strengthen military ties.
The meeting was the third for both leaders this year in the Russian capital.
Turkey and Russia, who support opposite sides in the war in Syria, are making "vigorous concerted efforts" to normalize the Syrian situation, Putin said. Neither Putin nor Erdogan mentioned a breakthrough on military action to remove rebel militants from Syria's Idlib region, a point of contention when the two world leaders last met in February.
The pair also discussed completing a deal to deliver a Russian defense system to Turkey's military, as the plan faces strong objection from the United States. U.S. Vice President Mike Pence warned last week Turkey must decide between NATO security and risking that partnership with "reckless decisions." The United States has threatened to expel Turkey from its Joint Strike Fighter program, which involves mutual deployment of F-35 fighter planes, if the deal with Russia is not rescinded.
The leaders also disagree over a Syria buffer zone to keep U.S.-backed Kurdish forces away from the Turkish border. Erdogan has said Kurdish forces are affiliated with militants in southeast Turkey, a charge the Syrian Kurds dispute.
Putin and Ergodan also agreed Monday to improve trade between the two nations. Erdogan said $25 billion in trade will be increased to $100 billion.
"Our cooperation with Russia continues increasing and becomes stronger," Erdogan said previously.