WASHINGTON - US airstrikes have killed several senior Islamic State (IS) leaders in recent weeks, blunting the group's ability to fight Iraqi and Kurdish forces, the Pentagon said on Thursday.

"I can confirm that since mid-November, targeted coalition airstrikes successfully killed multiple senior and mid-level leaders within the Islamic State of Iraq and the Levant (ISIL)", Pentagon Press Secretary John Kirby said in a statement, using the group's alternative name.

"We believe that the loss of these key leaders degrades ISIL's ability to command and control current operations against Iraqi Security Forces (ISF), including Kurdish and other local forces in Iraq," he said.

The success of these airstrikes demonstrates the coalition's resolve in enabling the ISF to disrupt and degrade IS as they continue to regain control of their territory, he added.

Meanwhile, another Pentagon statement said that US and partner-nation military forces continued airstrikes on IS targets in Syria and Iraq Thursday, using fighter and bomber aircraft during six airstrikes in Syria and five airstrikes in Iraq.

The airstrikes in Syria destroyed seven IS fighting positions and an IS building and tactical unit. In Iraq, they destroyed an IS excavator, three IS vehicle and two IS tactical unit.

On the same day, US President Barack Obama spoke by phone with Iraqi Prime Minister Haider al-Abadi to discuss the political and security situation in Iraq and the progress of Iraqi Security Forces in their efforts to counter IS.

The president reiterated his commitment to supporting the ISF through training programs, provision of weapons and equipment, and airstrikes.