The most immediate implication to the oil industry of the decision is to Royal Dutch Shell ( RDS.A.), which has been planning to begin a drilling project in the Arctic this summer, and had been working overtime to assure the federal government that it wouldn't be the next BP, once the oil spill crisis unfolded. >>Oil Spill in Pictures: Gulf of Mexico Impact New drilling permits will not be issued by the federal government until the cause of the BP oil spill is determined, and stricter safety and environmental rules are imposed on drillers. Thursday was a critical day in BP's fight against the oil spill, as an announcement was expected from the embattled oil giant as to whether its "top kill" effort to contain the leaking oil has worked. U.S. Coast Guard Rear Admiral, Thad Allen, told the Los Angeles Times on Thursday morning that the top kill had worked, and BP would next be moving to cement the leaking underwater well permanently shut. Previously, the Coast Guard official had been more guarded in his optimism, saying late on Wednesday that the lack of bad news in the top kill effort was encouraging news, and that the top kill plan was proceeding according to plan. There was no definitive word from BP or the government on Thursday afternoon. The oil giant is running out of options to contain an oil spill that has already leaked up to 7 million gallons of oil in the Gulf of Mexico. The Coast Guard Rear Admiral also delivered some distressing news amid his hopeful comments on the top kill, saying the new estimate for how much oil has been leaking into the Gulf of Mexico is between 12,000 to 25,000 barrels per day, well above the previous, heavily criticized estimate of only 5,000 barrels.