China pledged stronger cooperation with the international community to combat terrorism, as US President Barack Obama announced a "systematic campaign of airstrikes" against Islamic State militants "wherever they exist".

"America will lead a broad coalition to roll back this terrorist threat," Obama said in a Wednesday primetime address to the nation.

The Obama administration has been blamed for its slow reaction to Islamic State's activities.

Foreign Ministry spokeswoman Hua Chunying said on Thursday that "the lasting turbulence in some areas has given transnational terrorists a chance", posing new security threats and challenges for antiterrorist cooperation.

China expects that "the countries concerned will regain stability and orderliness at an early date", which will help eliminate the breeding ground of terrorism there, Hua said.

Hu Shisheng, a South Asia studies scholar at the China Institute of Contemporary International Relations, said that since the 9/11 attacks, the effects of the global anti-terror battle have rippled like a huge rock thrown into a swamp.

"Homeland security in the United States has been overhauled close to perfection, but some other countries, which have been home to terrorists, have suffered greater chaos and dysfunction of governance," Hu warned, adding that the mission against terrorism is now faced with unprecedented difficulties.

Li Shaoxian, an expert on Middle East affairs and vice-president of the China Institute of Contemporary International Relations, said Obama's declaration of such a campaign aims to impress on the public that "the US is returning to the fight against terror".

"Since Obama took office, the priority of the US global anti-terror campaign has diminished on the White House agenda, and the pressure on the extremist organizations has been partly relieved, which gave rise to the violent Islamic State," Li said.

Obama aims to "restore eroding US public confidence in his leadership and ability to safeguard national security", Xinhua commented.

Obama also said the US will not hesitate to take action against Islamic State in Syria as well as Iraq, indicating an expanded scale of attack.

Li questioned the effectiveness of using only airstrikes without ground forces.

"A chain reaction will be prompted if the US army enters Syria," he said.

China called upon the global anti-terror fight to respect international law, national sovereignty and territorial integrity, Hua noted.

zhangyunbi@chinadaily.com.cn