A top Coast Guard official Monday praised Royal Dutch Shell PLC's efforts to prepare for oil exploration in Alaska but noted that the company won't get its final permit for operations until it completes a long list of improvements to its oil spill response vessel.

As Shell prepares to drill for oil in the Beaufort and Chukchi seas, the company plans to deploy "22 vessels that are all designed either as ice vessels or anchor vessels, as skimmers, response vessels," Coast Guard Commandant Robert Papp said at a Senate hearing in Kodiak, Alaska.

"They will have everything in place and ready to go in an overabundance of caution in case something happens," he said at a field hearing of the Senate Homeland Security Appropriations Subcommittee. "We are looking at the worst-case discharge possibility, and I think Shell has well prepared for that. ... Quite frankly, I'm impressed with the amount of effort, work and commitment of resources that Shell has done."

However, the company's oil spill response vessel still faces "a list of things that need to be done before we can certify that it's safe to operate. Until the Arctic Challenger is released and gets up here, they will have to wait," he added.

Coast Guard officials say the Challenger, which is currently in Bellingham, Wash., still must complete hundreds of fixes before it can be approved, according to the Anchorage Daily News.

As global warming causes the Arctic waterways to remain open each summer, Papp said the Coast Guard is ready to assume additional responsibilities in the Arctic. But he noted that the Coast Guard faces serious budget constraints that are stretching thin its resources.

"When the ice was covering the Arctic almost full time, there was no human activity and we didn't need to deploy any Coast Guard resources up there," he said. "But now during the summer months when we're having much more open water ... we have responsibilities up there. We are the maritime law enforcement, first responder service for this country."

Subcommittee Chairwoman Mary Landrieu (D-La.) and Alaska Sen. Lisa Murkowski (R) used the hearing to call for more federal funding for icebreakers and other critical resources for the Arctic.

"While other countries like Russia and Canada are quickly building icebreakers to increase their presence in the Arctic, this administration and the last administration have been slow to respond," Landrieu said. "The alarm has sounded, but we keep hitting the snooze button."