TEHRAN, Iran — Russia’s President Vladimir Putin was in Tehran on Monday for talks with Iranian leaders expected to focus on the Syrian crisis and an international peace plan intended to end the conflict.

The visit comes as Russia, the United States, France and others are talking about possible joint action against the Islamic State group following the terror attacks in Paris and the downing of a Russian passenger jet in Egypt. Putin’s trip also comes on the heels of agreement on an incomplete peace plan that calls for talks between Syrian President Bashar Assad and his foes.

Moscow and Tehran have been the key backers of Assad throughout his nation’s civil war, which has killed over 250,000 people and turned millions into refugees. Russia has shielded Syria from international sanctions, and on Sept. 30 it launched an air campaign against the Islamic State group and other insurgents, while Tehran has sent military advisers to shore up Assad.

Putin, on a one-day visit to attend a gas exporting nations’ summit, is set to meet with Iran’s Supreme Leader Ayatollah Ali Khamenei and President Hassan Rouhani. Assad’s fate will likely dominate the agenda.