WASHINGTON (AFP) - Incoming US Defense Secretary Leon Panetta, who takes the helm at the Pentagon on Friday, is determined to avoid gutting the US military despite the prospect of difficult budget decisions.

Panetta, 73, who is stepping down as head of the CIA, is due to take over at 8:45 am (1245 GMT) from Robert Gates, who is retiring after more than four years on the job supervising troubled wars in Afghanistan and Iraq.

Panetta assumes office against the backdrop of mounting calls to rein in government spending, including the country's massive defense budget.

Pentagon spokesman Douglas Wilson said the budget would be an "important item on (Panetta's) agenda" but that the incoming secretary "believes that it is a false choice between fiscal responsibility and national security."

"He will take that very seriously. He knows there are difficult decisions to be made," Wilson said Thursday.

Panetta "has said publicly, and he will say again, that he intends that there will be no hollow force on his watch."

The vast defense budget for 2010 stood at $663 billion, accounting for more than 40 percent of the world's military spending, and a growing number of lawmakers say the Pentagon can no longer be excluded from cutbacks.

As secretary, Panetta will also be focusing on the wars in Afghanistan and Iraq and "is committed to succeeding and achieving America's goals on his watch," said Wilson, assistant secretary of defense for public affairs.

Panetta was due to meet the chiefs of the armed services Friday afternoon in "the tank," where top brass have deliberated over crises and wars for decades.

Panetta planned to have lunch with the US military's top officer, Admiral Mike Mullen, and his wife, ahead of the meeting, Wilson said.

Panetta's priority was to "reach out" to all levels of the military and hear from a broad range of service members, from enlisted ranks to mid-level and senior officers, he said.