The Obama administration is weighing moving U.S. troops closer to the front lines in Iraq and Syria while preparing to "intensify" the air campaign against the Islamic State, officials said Tuesday. 

Defense Secretary Ash Carter testified on Capitol Hill Tuesday that the military plans a "higher and heavier rate of strikes" against ISIS targets. 

Separately, a senior U.S. official confirmed to Fox News that President Obama is considering proposals to move U.S. troops closer to the front lines in the fight. The Washington Post first reported that national security advisers are proposing putting a limited number of Special Operations forces in Syria, and U.S. advisers closer to the fight in Iraq. 

The changes would need approval from Obama, but the plans reflect an effort to recharge the campaign against ISIS -- particularly after a U.S. train-and-equip program to help Syrian rebels was effectively ended. 

"The end state is to defeat ISIL," Joint Chiefs Chairman Gen. Joseph Dunford, Jr., testified before the Senate Armed Services Committee on Tuesday, acknowledging: "No one is satisfied with our progress to date." 

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At the same hearing, Carter described a changing approach to the fight against the Islamic State, focusing largely on Raqqa, the Islamic State-declared capital in Syria, and Ramadi, the capital of Anbar province in western Iraq. 

Carter said the U.S. would intensify the air campaign against the Islamic State with additional U.S. and coalition aircraft and heavier airstrikes. His testimony came as Russia is conducting its own airstrikes in Syria, saying it aims to help the Syrian government defeat the Islamic State and other terrorists. 

The U.S.-led effort "will include more strikes against IS high-value targets as our intelligence improves, and also its oil enterprise, which is a critical pillar of IS's financial infrastructure," he said. 

Carter said to keep up the pressure on Raqqa, the U.S. will support moderate Syrian forces, who have made territorial gains against the Islamic State near that city. 

"Some of them are within 30 miles of Raqqa today," he said. 

He said the U.S. also hopes to better equip Arab forces battling the Islamic State and to further bolster Jordan, a neighbor of Iraq and Syria which is flying missions as part of the anti-IS coalition. 

Carter said he was disappointed that the U.S. effort to form new moderate Syrian rebel forces to fight ISIS had failed. He said the new approach is to work with vetted leaders of groups that are already fighting the militants and also give them equipment and training and help support them with U.S. air power. 

The military leaders faced tough criticism Tuesday from committee Chairman Sen. John McCain, R-Ariz., who said "killing" the earlier training program is "destroying what little trust our Syrian partners have left in us to say nothing of allies like Turkey and Jordan that invested their own money and prestige in the program."   

He added, "We're still not providing sufficient support to Sunni tribes which are the center of gravity in this fight." 

The new strategy would include helping the Iraqi government's effort to assemble Iraqi forces, including Sunni fighters, to fight Islamic State militants in Anbar province. Carter said that as the U.S. sees more progress in assembling motivated Iraqi forces, it will be willing to continue providing more equipment and fire support to help them succeed. 

Fox News' Jennifer Griffin and The Associated Press contributed to this report.