The first two simultaneous exchange flights landed in the government city of Aden, carrying 35 people, and in the Houthi-held capital Sanaa, carrying 125, around midday on Friday, a Reuters witness and Houthi-run Al Masirah TV said.

The ICRC, which is managing the process, said its planes would be used to carry the released detainees between six cities in Yemen and Saudi Arabia over coming days.

“This release operation comes at a time of hope for Yemen as a reminder that constructive dialogue and mutual compromises are powerful tools capable of achieving great outcomes,” the U.N. Yemen Envoy Hans Grundberg said.

Warring parties agreed at negotiations in Switzerland last month to free 887 detainees and to meet again in May to discuss further releases.

Negotiators had hoped for an “all for all” deal involving all remaining detainees during the 10 days of talks held near the Swiss capital Bern. The talks were the latest in a series of meetings that led to releases of prisoners in 2022 and 2020 under a U.N.-mediated deal known as the Stockholm Agreement.

“Our deep desire is that these releases provide momentum for a broader political solution,” said Fabrizio Carboni, the ICRC’s regional director.

Yemen’s conflict, which has killed tens of thousands of people and left millions hungry, has widely been seen as a proxy war between Saudi Arabia and Iran.

A Saudi-led coalition intervened in Yemen in 2015 after the Iran-aligned Houthis ousted the government from Sanaa in 2014.

Riyadh and Tehran last month agreed to restore diplomatic ties severed in 2016, raising hopes that Yemen’s peace process would see progress.

A Saudi delegation on Thursday concluded peace talks in Sanaa with the Houthi movement whose officials cited progress and said further discussions were needed to iron out remaining differences.

(Reporting by Mohammed Alghobari and Fawaz Salman in Aden, Khaled Abdullah, Adel al-Khadher and Abdulrhman Al-Ansi in Sanaa; Writing by Lisa Barrington; Editing by Toby Chopra and Alex Richardson)