Azerbaijan released 15 Armenian prisoners of war in exchange for maps showing locations of nearly 100,000 landmines in territories that Armenia occupied during nearly three decades of conflict over the Nagorno-Karabakh region, according to a deal announced Saturday.

The accord, brokered by the U.S. and EU, marked a rare conciliatory gesture between the two bitter enemies in the South Caucasus. In a statement, the Azerbaijan Foreign Ministry thanked U.S. Secretary of State Antony Blinken, acting Assistant Secretary of State Phil Reeker, and European Council President Charles Michel, as well as the Organization for Security and Cooperation in Europe, currently chaired by Sweden.

Michel had a flurry of contacts with the leaders of Armenia and Azerbaijan, including a meeting with acting Armenian Prime Minister Nikol Pashinyan in Brussels earlier this month and a call with Azerbaijan President Ilham Aliyev the same day, in a push to complete the agreement. Michel has played an active diplomatic role in the region in recent months, having also helped to broker an accord in April to end a domestic political crisis in Georgia.

The government of Georgia assisted in carrying out the new deal, with the 15 prisoners released at the Azerbaijan-Georgian border.

Michel hailed the deal in a statement on Twitter, calling it a “first step towards renewing confidence.”

A baby-step might be more accurate, as Azerbaijan is believed to still hold dozens more prisoners, Armenia is believed to have additional maps of many more mines, and the enmity between the countries is extremely deep.

The latest chapter in the Nagorno-Karabakh conflict ended in November with a Russian-brokered ceasefire that amounted to a humiliating surrender for Armenia, after Turkey tipped the balance of a short brutal war in favor of Azerbaijan. Armenia surrendered territories that it had long occupied but were recognized internationally as belonging to Azerbaijan, and made other concessions. As part of the settlement, Azerbaijan also reclaimed parts of the Agdam region that long-served as a no-man’s land, and where Armenia had laid tens of thousands of anti-tank and anti-personnel mines.

“Obtaining mine maps will save the lives and health of tens of thousands of our citizens, including demining workers, and accelerate the reconstruction projects initiated by the President of the Republic of Azerbaijan, Mr. Ilham Aliyev, in Agdam and the return of IDPs,” the Azerbaijan Foreign ministry said in its statement.

The involvement of the EU and the U.S. in the agreement represents a return to some relevance in the region for the West, which had been left largely on the sidelines as Turkey intervened militarily, and then Russia interceded to broker a ceasefire. As part of the peace deal, Russian troops will be stationed in the region for years to come, securing continuing influence for Moscow.

Pashinyan, who is serving in a caretaker role and in the middle of a heated election campaign, had recently offered to trade his 21-year-old son, Ashot, for the release of prisoners of war.