U.S. Secretary of Defense Chuck Hagel gestures as he speaks during a press conference with Australia's Defense Minister David Johnston in Sydney, Australia, Monday, Aug. 11, 2014. Hagel is in Australia along with U.S. Secretary of State John Kerry for talks with government officials as part of the annual Australia-United States Ministerial talks.(AP Photo/Rob Griffith/Pool)

WASHINGTON (AP) — Defense Secretary Chuck Hagel says the U.S. and coalition forces are making progress against Islamic State militants. But he says the American people must prepare for a long and difficult struggle.

Hagel is testifying Thursday before a House panel. He cautions there will be setbacks in the fight in Iraq and Syria. He said that since September, 16 nations have joined the military campaign and carried out more than 130 air strikes.

Hagel’s testimony comes days after President Barack Obama asked Congress for more than $5 billion to expand the U.S. mission in Iraq. The president also is dispatching up to 1,500 more American troops to the war-torn nation, potentially boosting the total number to 3,100.

Congress also must decide whether to reauthorize training and equipping of moderate Syrian rebels.