WASHINGTON — Military leaders told lawmakers on Tuesday U.S.-Iraqi forces have made progress defeating the self-proclaimed Islamic State, but continued success would be impeded if automatic reductions in the defense budget take place.

Gen. Lloyd Austin, the commander of U.S. Central Command, said that the Islamic State is on the run because of American-Iraqi efforts. The extremist group has run out of space in the Middle East and has had to look elsewhere for territorial claims, he said.

Speaking before the House Armed Services Committee, Austin said the U.S. has made significant progress fighting ISIS forces in Iraq. More than 8,500 of the group’s fighters have been killed since airstrikes started in August, he said.

Austin said the U.S. continues to help Jordan, Lebanon and Turkey bolster its regional defenses against ISIS, and it will soon begin building ground troops in Syria as an additional defense measure.

Christine Wormuth, the Undersecretary of Defense Policy, said the U.S. has maintained its commitment to help Iraq rebuild security forces, adding that there are 2,600 members of the U.S. military currently leading these efforts on the ground in Iraq.

“We’re having significant effects on the enemy,” Austin said, but he added there is still a lot of work to do to achieve stability in the region.

Austin emphasized that creating a stable environment in Iraq would depend on the ability of its government to avoid sectarianism. He said the U.S. is working to ensure that Iraq is “ accommodating to the Sunni population, the Kurdish population that is in the country.”

The hearing opened with a summary of U.S. strategy in Iran, Iraq, Afghanistan, Syria and Yemen in the past year.

“This is not something that the U.S. can come up with a plan and go in and fix Syria, or fix Yemen, or fix Iraq,” said Washington Rep. Adam Smith, the top Democrat on the committee.

The so-called Islamic State, or ISIS, is an extremist military group operating in Iraq, Syria, and other parts of the Middle East, North Africa, and Southeast Asia. The U.S. has designated it a terrorist organization, and President Barack Obama has said the nation must “degrade and ultimately destroy” ISIS.

Austin said he is “absolutely confident” the U.S. can beat ISIS, adding, “I base that upon the progress we have made to date.”

Few representatives attended the hearing because of Israeli Prime Minister Benjamin Netanyahu’s address to a joint meeting of Congress. The committee recessed after opening testimony so lawmakers could attend the speech.

After the speech, Chairman Mac Thornberry, R-Texas, and other committee members asked Wormuth and Austin about U.S.-Israeli relations. “We have a very strong defense relationship with Israel,” Wormuth said.