U.S. Secretary of State Marco Rubio is sounding the alarm over a possible war between Ethiopia and Eritrea, warning that the last thing the world needs right now is another one. He said troops are surging on both sides of the border, and that anytime that happens in a place like this, there is a real worry it can spiral into a broader conflict. Rubio pointed to separatist attacks inside Ethiopia and drone attacks on the capital, acknowledged that Ethiopia responded, and urged all sides to be wise and measured so the situation does not escalate. Asked about Washington’s recent move to lift some small sanctions on Eritrea, he said they were minor and the goal was to improve communication, because it is hard to serve as mediator and peacemaker unless you can talk to both sides. He added that the U.S. has traditionally been closer to Addis Ababa, and he reportedly spoke with Ethiopian officials this week to stress a measured response.

The warning comes as the crisis has moved fast. Blasts rocked Addis Ababa on October 1, a rebel alliance claimed drone strikes on the capital including military targets, Ethiopia ordered Eritrean diplomats out and moved to close its embassy in Asmara, and Eritrea reportedly cut diplomatic ties. Ethiopia accuses Asmara of sending troops into Tigray and backing the rebels, and conflict monitor ACLED reported Eritrean troops crossing the border before coming under Ethiopian drone attack, while Eritrea denies it and calls the accusations a pretext to seize the port of Assab. Ethiopian forces and allied militias have since entered Adigrat, about 30 kilometers from the Eritrean border, and the two governments have traded accusations at the United Nations. With the State Department urging both sides to show restraint, analysts warn that a clash could pull in neighbors such as Sudan and Egypt, which Ethiopia accuses of backing the rebels and which deny it, and could disrupt Red Sea shipping.