A new government report by the U.S. Coast Guard and the agency that regulates offshore drilling blasts BP management for decisions that added risk and possibly led to last year’s devastating oil spill in the Gulf of Mexico. The Deepwater Horizon well exploded in April 2010, killing 11 workers and unleashing the worst oil spill in U.S. history. BP, the report says, was negligent in the placement of a cement seal that was put in place just a day before the explosion. Other investigations have blamed a variety of factors, including faulty data readings and the failure of the well’s blowout preventer. But this report places most of the responsibility on BP executives, who made decisions that complicated the sealing of the well and made the operation risky.