US President Barack Obama acknowledged on Tuesday that the fight against the Islamic State group is "a long-term campaign", after recent bombing raids against the group failed to produce significant progress on the battleground.

"This is going to be a long-term campaign. There are no quick fixes involved," Obama said after a meeting with coalition military leaders at Joint Base Andrews in Maryland.

There are "going to be periods of progress and setbacks", he added.

In the past two days, the coalition has conducted 21 attacks on the militants near the Syrian border town of Kobane, where Kurdish fighters are struggling to repel an onslaught by the Islamist group.

Despite the allied firepower, Islamic State forces have reportedly captured a military training camp in western Iraq and lobbed bombs at Baghdad suburbs, sparking concerns that the Iraqi military is not up to the fight.

The militants now control nearly half of Kobane and seized most of Iraq's largest province, Anbar.

"What we're also fighting is ideological," Obama said, calling for the US and the rest of the 60 nations participating in the effort against the Islamic State group to be "united in our goal".

But the White House maintained that despite some of the troubling news, the president's plan against the Islamic State group is "succeeding".

"We're in the early days of the execution of that strategy," White House Press Secretary Josh Earnest said at a news conference on Tuesday. "But certainly the early evidence indicates that this strategy is succeeding."

Earnest pointed out that US humanitarian missions successfully protected Iraqi minorities under siege from the Islamic State group, and had also driven the group from a pair of crucial dams.

But he also conceded that without ground forces, the United States would not be able to prevent all Islamic State advances.

"I don't think anybody has sought to leave you or anyone else with the impression that these kinds of airstrikes were going to dramatically reverse the situation on the battlefield overnight. They won't. We've been pretty candid about the fact that this is a longer-term proposition," Earnest said.

The plight of the Syrian Kurds in Kobane has also provoked riots among Turkey's 15 million Kurds last week, in which at least 35 people were killed.

The Kurds were angry over their government's refusal to help the coalition fight against the Islamic State group, while Ankara is wary of the Syrian Kurds and their Kurdish militia, which it believes is affiliated with southeast Turkey's Kurdish PKK movement, which has waged a long and bloody insurgency against the Turkish state.

Turkey further complicated issues on Tuesday when officials in Ankara said that Turkish jets bombed Kurdish rebel targets in the southeast of the country, the first such strikes against the separatists since an increasingly fragile 2013 cease-fire.

During the three-year civil conflict in Syria, about 1.2 million refugees have fled into Turkey, including 200,000 Kurds who fled the area around Kobane in recent weeks.

(China Daily 10/16/2014 page11)