Brazil, which has South America’s second-largest oil reserves, is favored to host COP30 in 2025.

Azerbaijan and Armenia — which have fought for control of contested territory since the dissolution of the Soviet Union — issued a joint statement Thursday saying Armenia would support Azerbaijan’s bid to host the climate talks.

The announcement also included promises to exchange service members who had been captured by each country in recent fighting.

The deal could break a diplomatic impasse that threatened to throw the international climate negotiations into chaos as nations deadlocked on where to host COP29.

The annual conference was set to return to Eastern Europe next year. But Russia opposed the bids of every European Union candidate because the bloc has backed Ukraine against Moscow’s invasion. Meanwhile, Azerbaijan and Armenia had vowed to block each other’s proposals due to their own protracted hostilities.

Without naming Russia, the joint statement said the countries “do hope” other Eastern European nations “will also support Azerbaijan’s bid to host.”

Armenia and Azerbaijan “will continue their discussions regarding the implementation of more confidence building measures, effective in the near future and call on the international community to support their efforts that will contribute to building mutual trust between two countries and will positively impact the entire South Caucasus region,” the statement said.

The State Department and Russia’s U.S. embassy didn’t immediately respond to requests for comment. The agreement was first reported by Reuters, which separately reported that Moldova and Serbia are also eyeing the influential COP presidency next year.

It comes at the midway point of this year’s COP in the UAE, whose reluctance to embrace calls to phase out fossil fuels has been a major sticking point in the summit.

It could foreshadow future impasses over energy. The economy of Azerbaijan, which is positioned between Iran and Russia, relies on fossil fuels for about 90 percent of its exports.

Brazil, which is expected to host COP30 in two years, moved last week to join the oil cartel OPEC+. That summit will feature the second round of national climate pledges required under the Paris Agreement.