WASHINGTON – US President Barack Obama on Wednesday called for cutting defense spending by $400 billion over 10 years as part of a deficit reduction plan.

Wading into difficult political terrain, Obama's proposal calls for "deeper reductions in security spending," according to a White House statement providing details of the president's plan.

"Just as we must find more savings in domestic programs, we must do the same in defense," Obama said in a high-stakes speech earlier.

Obama said that Defense Secretary Robert Gates had already shown political courage by cutting waste in military spending and finding $400 billion in savings over the past two years.

"I believe we can do that again," Obama said.

But he said deep cuts would first require an elaborate assessment of the country's military missions.

"We need to not only eliminate waste and improve efficiency and effectiveness, but conduct a fundamental review of America?s missions, capabilities, and our role in a changing world," the president said.

According to the White House, Obama's plan "sets a goal of holding the growth in base security spending below inflation, while ensuring our capacity to meet our national security responsibilities, which would save $400 billion by 2023."

The White House did not specify what weapons programs or missions might have to be cut to meet the goal.

It also did not say if the figure covered Defense Department funds only or spending by other government departments related to national security.

Part of the savings could come from the scheduled withdrawal of the remaining US troops from Iraq by the end of the year as well as a planned drawdown of forces in Afghanistan starting in July.

Republicans and some Democrats in Congress tend to view defense spending as sacrosanct, seeking to find savings elsewhere in the federal budget.

But fiscal pressures have prompted calls to consider scaling back the country's vast defense budget, by far the largest in the world.