US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov led a meeting of top diplomats from UN veto powers and the Middle East in Vienna on Tuesday, aimed at strengthening the fragile Syrian truce and reviving peace talks.
It was the first meeting of the International Syria Support Group since February, when its members brokered a ceasefire that has become increasingly frayed over the past weeks.
"Today will be about creating conditions so that the agreed cessation of hostilities is better enforced, so that not only the city of Aleppo but also the region of Aleppo returns to calm," German Foreign Minister Frank-Walter Steinmeier told reporters, referring to one of the main flashpoints of violence.
The Syria contact group consists of 17 countries that have backed both sides in the civil war and used their influence with the regime and the armed rebels to establish a truce.
The US government backs the rebels, while Russia supports Syrian President Bashar al-Assad.
The Vienna talks also include top diplomats from regional foes Saudi Arabia and Iran, which back the rebels and the regime, respectively.
UN-brokered peace talks in Geneva ended last month without any progress after the delegation of the opposition walked out, citing surging attacks by regime forces and its Russian ally, as well as problems with humanitarian aid shipments.
The foreign ministers are expected to explore ways to bring the opposition back to negotiate political change with the regime of President Bashar al-Assad, by helping to strengthen the truce and to improve aid efforts, Steinmeier said.
"This change is necessary because Syria will not be able to build a future in the long term with al-Assad in power," Steinmeier added.
While the Syrian opposition demands that the president step down and pave the way for a political transition, the government delegation in Geneva has so far refused to talk about such a scenario.
Iranian Foreign Minister Mohammad Javad Zarif said his country supported the truce and a peace dialogue, but he warned that a silence of arms might aid terrorist groups operating in Syria.
"We should not allow terrorists to use the cessation of hostilities for further terror operations," he said.
The truce deal does not cover the extremist groups Islamic State and al-Nusra Front, al-Qaeda's Syria branch.