Defense Secretary Ashton Carter said Sunni nations must do more to support the U.S.-led coalition fighting Islamic State terrorists in Iraq and Syria, offering his most direct public criticism of inaction by Gulf allies such as Saudi Arabia.
"It's strange that a Sunni extremist group running rampant in Iraq and Syria should attract as little Sunni Arab counterweight as it has so far," Carter said Friday in an interview in Davos, Switzerland, with Bloomberg Television. "I would look to galvanize that."
Members of the coalition will meet in Brussels in three weeks in a session Carter said is aimed at intensifying the fight against the terrorist group that holds a swath of Iraq and Syria. While the United States will be the leader in the fight, as "we always are," Carter said, many nations "are doing nothing or not nearly enough."
"We need others to carry their weight," he said, without mentioning any countries by name. "There should be no free riders."
Saudi Arabia and some of its Gulf neighbors initially participated in airstrikes against Islamic State, but their participation trailed off as they concentrated on the war against Houthi rebels in Yemen.
Beyond airstrikes, Carter said Sunni nations could play an effective role on the ground.
"Remember, those countries can do something that it's very difficult for us to do," Carter said in the interview on "Bloomberg " from the annual World Economic Forum. "We can enable local forces to seize territory and hold territory. But we know from our own difficult experience there that, in the end, somebody else has to take over. Somebody else has to run these places. Somebody else has to govern these places. It can't be done from the outside in."
The U.S. has been pressing Iraq's Shiite-dominated government to enlist Sunni tribes in the war effort to bridge sectarian gaps. Ramadi, a strategically important, mostly Sunni city, was recaptured in late December without the help of formidable Shiite militias, after falling to Islamic State in May.
Now, Sunni tribesmen trained by the U.S. are helping to hold the city. About 6,000 Sunni have been trained so far this year, with hundreds more trainees in the pipeline, Army Colonel Steve Warren, the top U.S. spokesman in Iraq, said in an e-mail.
The importance of enlisting Iraqi Sunnis in the fight against Islamic extremism was demonstrated during the 2007 George W. Bush administration "surge" of U.S. troops to quell an al-Qaida-led insurgency that almost defeated the U.S. That "Anbar Awakening" of Sunni tribesman, who fought and defeated insurgents as part of a "Sons of Iraq" program, has been acknowledged as key to turning the tide of a civil war.