A frame grab, taken from a BP live video feed, shows machinery being used in the “top kill” procedure to stop the flow of oil from the Gulf of Mexico oil well

A frame grab, taken from a BP live video feed, shows machinery being used in the “top kill” procedure to stop the flow of oil from the Gulf of Mexico oil well May 26, 2010. BP Plc launched an ambitious deep sea operation to choke off a gushing oil leak in the Gulf of Mexico on Wednesday, but President Barack Obama cautioned Americans there was no guarantee it would work. Reuters/Handout (UNITED STATES – Tags: DISASTER ENERGY ENVIRONMENT IMAGES OF THE DAY BUSINESS) NO SALES. NO ARCHIVES. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS