Martin Dempsey
Martin DempseyReuters

The Chairman of the United States Joint Chiefs of Staff on Sunday defended the pace of the air war against Islamic State (ISIS) jihadists, warning that escalating bombing raids or sending in more American troops would be a mistake.

During a visit to a French aircraft carrier in the Gulf taking part in the air campaign, General Martin Dempsey appealed for "strategic patience" in the fight against the ISIS group in Iraq and Syria, according to AFP.

Expanding the air war could risk civilian casualties and play into the hands of ISIS propaganda, he said aboard the Charles de Gaulle.

"So we have a responsibility to be very precise in the use of air power. And that means that it takes time" to gather accurate intelligence on possible targets, Dempsey said, adding, "Carpet bombing through Iraq is not the answer."

The tempo of military operations also depended on the strength of the Iraqi army and the Baghdad government's willingness to reconcile with an alienated Sunni population, he said.

The conflict could be decided on the battlefield relatively quickly, but military operations were only part of a broader effort, said Dempsey.

"I do think it's going to require some strategic patience," he said, adding that "these underlying issues have to be resolved".

Dempsey spoke in the carrier's hangar alongside his French counterpart, General Pierre de Villiers, who said he shared the American general's view.

The coalition faced a "paradox" as Western countries wanted "quick results", but the Iraqi army had to be rebuilt before it could take back territory from the ISIS extremists, de Villiers said.

Despite the pleas for a deliberate approach, Iraq on Sunday urged the international coalition to use its air power to help protect the country's archaeological sites before ISIS extremists destroyed more precious artifacts.

"We request aerial support," said Iraq's tourism and antiquities minister, Adel Fahad al-Shershab.

Recent attacks on Iraq's historic heritage have taken place in the northern province of Nineveh, where Baghdad lacks troops on the ground.

On Saturday it was reported that ISIS terrorists had destroyed the ancient city of Hatra, a stunning Roman period ancient fortress city in the Iraqi desert. The group previously began bulldozing the ancient Assyrian city of Nimrud and before that  released a video showing its members armed with sledgehammers and jackhammers smashing priceless ancient artifacts at the Mosul museum.

Washington has faced criticism from some Arab allies that the air campaign launched in August is ineffective and overly cautious.

Hawkish American lawmakers have called for sending in more special operations forces to help guide Iraqi troops in combat and direct air strikes.

But Dempsey said there was no need to increase the number of American troops advising and training local forces, as the Iraqi army was not ready for a larger-scale effort.

"We've got trainers and advisers that are waiting for some of the Iraqi units to show up," the general said of the 2,600-strong U.S. contingent. "And when they've shown up, a handful of them, they've shown up under strength and sometimes without the proper equipment."