Obama: ISIS Has Lost 40% of Its Iraqi Territory

'You are next,' Obama tells ISIS leadership as U.S. defense secretary travels to region to strengthen military support of coalition.

President Barack Obama addresses the nation from the Oval Office at the White House in Washington, Sunday night, Dec. 6, 2016.

REUTERS - U.S. President Barack Obama said on Monday that the Islamic State group has lost 40 percent of the areas it once controlled in Iraq because of the U.S.-led coalition airstrikes, and vowed to target the group's leaders.

"ISIL leaders cannot hide and our next message to them is simple: 'you are next,'" he said, using an acronym for the group.

The coalition was also targeting Islamic State's oil tanker trucks, wells and refineries: "We are hitting ISIL harder than ever," Obama said. 

Nonetheless, the president said progress needs to speed up in the fight against Islamic State militants, and called on allies to increase their military contributions to the coalition working to destroy the group's presence in Iraq and Syria.

Speaking to reporters at the Pentagon, Obama said he was sending Defense Secretary Ash Carter to the Middle East to secure more military help from partner nations in the fight against the group. 

"This continues to be a difficult fight," Obama said. "We recognize that progress needs to keep coming faster." 

The president ticked off a list of accomplishments by the United States and its allies against the group: Islamic State had lost significant swaths of territory it once controlled in Iraq and Syria, and leaders were being targeted one by one.

Obama, a Democrat, has come under criticism by Republicans for not doing enough to counter Islamic State, in particular since the November 13 attacks in Paris that killed 130 people and were claimed by Islamic State, and the December 2 shooting in San Bernardino, California. Authorities believe the couple who killed 14 people in that attack were inspired by Islamist militants. 

The White House has sought to counter those critics by outlining progress made since Islamic State's rapid rise in Iraq and Syria more than a year ago.