The Tohono O'odham Nation closed its tribal lands to non-members today, and placed 'No Trespass' signs at its borders, as it continues to fight border wall construction on its sovereign land. Tohono O’odham Nation leadership has been informed that federal contractors may attempt to enter the Nation’s lands this weekend to begin conducting work related to border wall construction. Tohono O’odham law enforcement is on alert to turn back trespassers," the Tohono O'odham Nation said today. The Nation's attorneys in Washington are seeking a preliminary injunction to prevent the border wall construction by the U.S. Department of Homeland Security. "Only Congress has the authority to diminish the reservation, not DHS," the Tohono O'odham Nation said in a statement on Monday.