SOUTH PADRE ISLAND, Texas - Rear Adm. Roy Nash, commander of the Eighth Coast Guard District, signs the update to the 2012 MEXUSGULF Annex at the Isla Grand Beach Resort, Apr. 26, 2012.The annual MEXUS exercise involves hundreds of participants from Gulf Coast states and Mexico, in which a major oil spill threatens both Mexican and U.S. coastal areas. Official U.S. Coast Guard photo by Petty Officer 3rd Class Richard Brahm.