New Orleans, Louisiana (CNN) — The U.S. military may be called on to assist authorities scrambling to mitigate a potential environmental disaster posed by an oil spill expanding toward the  Gulf Coast, the Coast Guard said Thursday.

In addition, another controlled burn of the oil slick may be conducted, Coast Guard Chief Petty Officer Erik Swanson said.

Officials said late Wednesday the estimated amount of oil spewing into the Gulf of Mexico from three underwater leaks after last week’s oil rig explosion has increased to as much as 5,000 barrels,  or 210,000 gallons, a day — five times more than what was initially believed.

The cause of the explosion remains under investigation, and search efforts have been halted for 11 missing workers.

Rear Adm. Mary Landry told reporters late Wednesday that the increased estimate is based on analysis from the National Oceanic and Atmospheric Administration.

“This is not an exact science when you estimate the amount of oil,” Landry said, noting there are a lot of variables in calculating the rate of the spill.

“However, NOAA is telling me now that they prefer we use the 5,000 barrels a day as an estimate of what has actually leaked from this well and will continue to leak until BP secures the source.”

Some 250,000 gallons of oily water have been collected from the scene, she said.

BP is the owner of the well, while Transocean Ltd. owns and operates the rig.

“I do not disagree with the admiral’s estimate that it could be 5,000 barrels a day — it’s clearly within the range of uncertainty,” said Doug Suttles, chief operating officer for BP, who joined Landry at Wednesday’s news conference.

Top operations planners briefed Adm. Michael Mullen, chairman of the Joint Chiefs of Staff, on Thursday morning in anticipation of the possible request for assistance from the Coast Guard, said spokesman Capt. John Kirby.

Mullen was told the weather is worsening, and the oil is set to reach the Louisiana coast Friday, Kirby said. Wind patterns out of the Southeast over the next few hours are increasing the likelihood the oil will come ashore.

“This is just prudent military planning,” Kirby said. “This thing is not getting better.”

Military planners on Wednesday night began examining options to provide assistance to the Coast Guard in cleaning up the spill, said James Graybeal, a spokesman for U.S. Northern Command in Colorado Springs, Colorado. The Northern Command is responsible for coordinating and providing military assistance inside the United States.

The military could put a ship in the Gulf to support and resupply other vessels in the region or provide aircraft to help map the spill.

The military also may offer to establish a supply base along the coast to stage equipment and other supplies for the Coast Guard and the overall cleanup effort, according to a U.S. military source. The military has larger bases and the ability to stage equipment for a longer-term operation, the source said. In addition, the U.S. Navy has booming equipment it can use.

Officials are trying to get resources on land, place booming equipment around the spill and have personnel ready to go when the oil reaches land.

Drilling a relief well — a second well drilled up to a mile or two away that would enter the leaking well at an angle to help plug it — takes time, Swanson said.

The first rig to be used for drilling the relief well will begin drilling about a half-mile from the leaking well Friday, NOAA said. However, the relief well “will not be complete for several months,” it said.

In addition, a collection dome will be deployed to the sea floor to collect oil as it leaks from the well, NOAA said. Workers have finished fabricating the containment chamber portion, and “work will now begin on the piping system that brings the oil to the surface for collection; this method has never been tried at this depth before.”

Another burn of the oil is “certainly an option,” the Coast Guard’s Swanson said. “We utilized it yesterday. We were able to do a test burn, which was successful, and we’re going to see if we can do that today, pending good weather.”

BP and the Coast Guard corralled part of the oil slick using a 500-foot, specially designed boom, and then set it ablaze. The flames were expected to destroy between 50 percent to 90 percent of the oil in that section, and winds were expected to blow the resulting cloud of smoke and soot out to sea, Lt. Cmdr. Matt Moorlag, a Coast Guard spokesman, said before Wednesday’s burn.

The oil spill has the potential to become one of the worst in U.S. history, the Coast Guard’s Landry said earlier.

The head of BP Group told CNN’s Brian Todd in an exclusive interview Wednesday that the accident could have been prevented, and he focused blame on rig owner Transocean.

CEO Tony Hayward said that Transocean’s blowout preventer failed to operate before the explosion. A blowout preventer is a large valve at the top of a well, and activating it will stop the flow of oil. The valve may be closed during drilling if underground pressure drives up oil or natural gas, threatening the rig.

“That is the ultimate fail-safe mechanism,” Hayward said. “And for whatever reason — and we don’t understand that yet, but we clearly will as a consequence of both our investigation and federal investigations — it failed to operate.

“And that is the key issue here, the failure of the Transocean BOP,” Hayward said, describing the valve as “an integral part of the drilling rig.”

A Transocean spokesman on Wednesday declined to respond to Hayward’s comments in the CNN interview, citing pending litigation against both companies.

However, Transocean Vice President Adrian Rose has said its oil rig had no indication of problems before the explosion.

Asked whether the accident could have prevented, Hayward said, “All accidents can be prevented — there’s no doubt about that.”

At least one of the victims’ families has filed a lawsuit against BP and Transocean, accusing BP specifically of negligence.

“The responsibility for safety on the drilling rig is with Transocean,” Hayward added. “It is their rig, their equipment, their people, their systems, their safety processes.”

He insisted that, despite reports to the contrary, BP has not resisted attempts at tightening safety regulations.

“We welcome tighter safety regulations. But we’d like them to be applied in a way that makes them practically impermeable.”

The slick stretched about 100 miles across the north-central gulf Wednesday afternoon and had advanced to within 16 miles of the mouth of the Mississippi River, the U.S. Coast Guard reported.

Louisiana Gov. Bobby Jindal said the slick was expected to hit the state’s southeastern shoreline later this week.

Jindal said the state has asked for 55,000 feet of booms to keep oil away from the marshy, environmentally delicate coast that’s rich in shellfish and wildlife.

“We want to approach this situation the same way we would approach a hurricane or other natural disaster,” he said. “We think it’s best to hope for the best, but prepare for the worst.”

Most of the slick is a thin sheen on the water’s surface. About 3 percent of it is a heavy, puddinglike crude oil.

Efforts already are under way to position boom material around sensitive ecological areas. Five staging areas have been set up on land, stretching from Venice, Louisiana, to Pensacola, Florida.

CNN’s Barbara Starr contributed to this report.