BUSAN, South Korea— The UNESCO World Heritage Committee published a decision today that clears the way for an international mission to urgently assess damage caused by the U.S. border wall to Mexico’s El Pinacate and Gran Desierto de Altar Biosphere Reserve and its wildlife.

“This decision sets a firm deadline, and I’m hopeful it will push the United States to act before more damage is done to El Pinacate by Trump’s border wall,” said Alejandro Olivera, senior scientist and Mexico representative at the Center for Biological Diversity. “The U.S. border wall isn’t just destroying habitat in the United States, it’s also severing wildlife corridors and harming a World Heritage site in Mexico. The Trump administration hasn’t done anything meaningful to repair the harm it’s caused south of the border, and that needs to change.”

The decision directs Mexico to urgently organize a joint “reactive monitoring” mission, without U.S. participation. The mission had been delayed because the United States previously declined to participate.

Today’s decision allows the mission to proceed despite U.S. nonparticipation and calls for an international assessment of the wall’s harms to the World Heritage site and disruptions to ecological connectivity with protected areas in Arizona — Organ Pipe Cactus National Monument and Cabeza Prieta National Wildlife Refuge. The mission will be conducted by the World Heritage Centre and the International Union for Conservation of Nature.

The committee also gave the United States until Dec. 1, 2026, to develop, fund and implement an urgent action plan, in cooperation with Mexico, to restore ecological connectivity. It warned that El Pinacate could qualify for inclusion on the List of World Heritage in Danger if connectivity is not restored to protect wildlife populations such as the endangered Sonoran pronghorn.

The decision asks the United States to submit the results of ongoing research on the wall’s harm to mammal communities when that information becomes available in 2027. It also calls on both countries to continue implementing the Sonoran Pronghorn Recovery Plan and strengthen population monitoring.

The World Heritage Committee met in Busan, South Korea, in July, but the final decision was not published until this week. The decision was not put to a vote on the meeting floor; after its consideration was delayed, the final text was resolved through closed-door consultations. As a result, the outcome remained uncertain until today.

The United States is not currently a member of the World Heritage Committee and the Trump administration announced its withdrawal from UNESCO, effective Dec. 31, 2026.

The border wall extends along nearly the entire boundary between Mexico’s El Pinacate and Arizona’s Organ Pipe Cactus National Monument and Cabeza Prieta National Wildlife Refuge. UNESCO has repeatedly found that the wall harms the integrity of El Pinacate by blocking wildlife movement across the Sonoran Desert.

Mexico must report on the condition of El Pinacate and implementation of the committee’s requests by Dec. 1, 2027. The report will be reviewed at the committee’s 50th session.

The Center and other conservation organizations, together with representatives of the Tohono O’odham Nation in Mexico, petitioned UNESCO in 2017 to designate El Pinacate as a World Heritage site “in danger” because of the border wall. The Center renewed that call in a 2023 letter.