Panama seized a shipment of military equipment bound for the U.S. Southern Command and the ship carrying it, saying that the shipment violated the Panama Canal Treaties. Atty. Gen. Carlos Villalaz said the equipment may have been destined for groups opposed to the regime of Gen. Manuel A. Noriega. A spokesman for the Southern Command, which is headquartered in Panama, denied the allegation, saying that Panama had acted illegally and that the United States has "vigorously protested." Villalaz said customs agents found a cannon and other war materiel in cargo containers aboard the American ship Ambassador. Another official, Lt. Col. Aquilino Sieiro, said the Americans were attempting to unload the materiel at a civilian port in violation of the canal treaties.