Speaking during a visit to Guam, Kempthorne compared the U.S. island territory to a canoe that wouldn't move forward if only a third of the boat were to benefit from economic improvements. The federal government controls about a third of Guam's land area.

The U.S. and Japan are spending some $10 billion to move more than 8,000 Marines and their families to Guam from densely populated Okinawa in southern Japan.

"While Guam will derive great economic benefits from the military build-up, the government will need assistance in preparing the territory's infrastructure for the influx of so many thousands of people over a relatively short time," Kempthorne said. "The Interior Department stands ready to help."

The Marines' arrival could add an additional 30,000 people to the island's population of about 170,000.

Guam Gov. Felix Camacho said Friday the U.S. island territory would need more than $1 billion in infrastructure upgrades to its power, wastewater and trash disposal systems to handle the increase.

The secretary met Camacho, Lt. Gov. Michael Cruz, members of the Guam Legislature, and Navy and Air Force representatives during his two-day stay.

He also spoke with the Guam Civilian-Military Task Force.

Kempthorne's department has overall responsibility for federal policy in the U.S. island territories.

The secretary visited Ritidian Point National Wildlife Refuge for a first-hand look at efforts by the U.S. Fish and Wildlife Service and the U.S. Geological Survey to eradicate the invasive brown tree snake.

Native to Southeast Asia, the species has devastated the native bird populations of Guam, and experts are worried it could spread to Hawaii and other sensitive ecosystems in the Pacific. Both agencies are overseen by the Department of the Interior.