Iran’s military presence in Syria was discussed during a second day of critical talks held between representatives of Turkey, Russia and Iran in the Russian Black Sea resort of Sochi, Russia’s official TASS news agency reported July 31. The talks are aimed at helping resolve the Syrian conflict.

TASS quoted unnamed sources as saying, “This issue was raised. The parties have different approaches to some details related to Iran’s presence in Syria.” The sources did not elaborate.

On the first day of the talks, the sides agreed to a prisoner swap between the regime and opposition rebels, part of a set of confidence-building measures, reported Turkey’s Hurriyet Daily News.

Russian President Vladimir Putin’s special envoy for Syria, Alexander Lavrentiev, said the talks were being held “in a routine and constructive manner.” He declined to comment further, noting that a final communique would be issued later in the day. Iran’s military presence in Syria, which is hotly contested by the United States and Israel, is but one of a host of thorny issues under discussion. The establishment of a Syrian constitutional committee and the return of millions of Syrian refugees from Turkey, Lebanon and Jordan were also on the table.