U.S. Secretary of State John Kerry said on Sunday he hoped to make progress in talks in Geneva over the next two days toward renewing a cessation of hostilities agreement throughout Syria and resuming peace talks to end the fighting.

“The hope is we can make some progress,” Kerry said at the start of a meeting with Jordan’s Foreign Minister Nasser Judeh shortly after arriving in Geneva.

“These are critical hours, we look for Russia’s cooperation, and we obviously look for the regime to listen to Russia and to respond.”

Kerry’s hastily arranged visit to Geneva followed a call by the U.N. envoy to Syria, Staffan de Mistura, to the United States and Russia to salvage a two-month ceasefire in Syria after fierce fighting in the city of Aleppo.

Moscow and Washington brokered the Feb. 27 ceasefire deal, which applied to western Syria but excluded al Qaeda and Islamic State fighters. World powers and the United Nations have been trying to salvage that truce.

The Syrian army announced on Friday a “regime of calm”, or lull in fighting, which applied to Damascus and some of its outskirts, and parts of northwestern coastal province Latakia. But it excluded Aleppo.

Kerry made clear that a ceasefire was needed throughout Syria and he hoped to be able to reaffirm the cessation of hostilities after talks in Geneva. He is due to meet Saudi Foreign Minister Adel al-Jubeir and De Mistura on Monday.

“I hope that in the course of the conversations I have here tonight, tomorrow, and the work that the teams are doing… (we can) zero in and pin down the modalities of reaffirming the cessation,” he said.

Judeh described the situation around Aleppo as “quite alarming” and said a cessation of hostilities was necessary for Syrian peace talks and humanitarian aid deliveries to resume.

“We have to address the situation on the ground today asserting a nationwide cessation of hostilities that will lead to a better and more conducive environment for the political track,” Judeh said.

He added: “It is en entire package: the cessation of hostilities, the negotiations, and the humanitarian access. All three of them are being challenges and we have to address that today.”

Kerry and Judeh said they would also discuss the Israeli-Palestinian conflict.

Judeh said the absence of a “negotiating track” in that dispute was a challenge that threatened stability in the region and beyond.