The signs read in English and Spanish, "Warning: Restricted Area," and had been declared restricted by "the commander."

On Monday, men arrived in a boat at a beach in northeast Mexico and installed some signs signaling land that the U.S. Department of Defense considered restricted.

Mexico’s Foreign Affairs Ministry said late Monday that the country’s navy had removed the signs, which appeared to be on Mexican territory. “The origin of the signs and their placement on national territory were unclear,” the ministry said in a statement.