Jordan announced it has carried out dozens of air strikes on the Islamic State group, as a top US envoy said Iraqi troops would begin a major ground offensive against the jihadists in the weeks ahead.
Jordanian air force chief Major General Mansour al-Jobour said Sunday the kingdom had launched 56 air raids since Thursday as part of an international assault against IS that Washington says is beginning to bite.
Jordan has vowed an "earth-shattering" response after the Sunni extremists captured one of its air force pilots, Maaz al-Kassasbeh, burned him alive and released a gruesome video of the execution.
"On the first day of the campaign to avenge our airman Maaz al-Kassasbeh, 19 targets were destroyed, including training camps and equipment," Jobour told reporters.
John Allen, the US coordinator for the anti-IS coalition of Western and Arab countries, said Sunday that Iraqi troops would begin a major ground offensive against the jihadists "in the weeks ahead".
"When the Iraqi forces begin the ground campaign to take back Iraq, the coalition will provide major firepower associated with that," he told Jordan's official Petra news agency, stressing that the Iraqis would lead the offensive.
IS have seized swathes of Iraq and Syria, ruling the territory with a brutal form of Islam.
- IS barracks hit -
Jordan has vowed to crush the group after they released a highly choreographed video showing the murder of its pilot, who was captured in December when his F-16 warplane went down in Syria.
The air force chief said air strikes since last Thursday had destroyed dozens of targets, including barracks, training camps, ammunition and fuel depots, and residential centres.
"So far, the campaign has destroyed 20 percent of the fighting capabilities of Daesh," Jobour said, using another name for IS.
Jobour said more than 7,000 IS militants had been killed since Jordan began participating in coalition air strikes.
US Secretary of State John Kerry said the aerial campaign, launched in September, was beginning to win back territory and deprive the jihadists of key funds.
There have been 2,000 air strikes on IS since the coalition's formation in August, Kerry told a security conference in the German city of Munich.
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The air war has helped to retake some 700 square kilometres (270 square miles) of territory, or "one-fifth of the area they had in their control", he said.
The top US diplomat did not specify whether the regained territory was in Iraq or Syria.
But he added the coalition had "deprived the militants of the use of 200 oil and gas facilities... disrupted their command structure... squeezed its finance and dispersed its personnel."
State media reported that a squadron of United Arab Emirates F-16 fighter jets arrived in Jordan on Sunday, escorted by pilots and technicians.
The UAE had withdrawn from the coalition's strike missions after the Jordanian pilot's capture over fears for the safety of its own airmen.
But the US had said on Friday that UAE flights were likely to resume "in a couple of days".
C-17 transporters and refuelling planes were part of the UAE squadron sent on the orders of Abu Dhabi Crown Prince Mohammed bin Zayed al-Nahayan, the Petra news agency said.
- Turning point for Jordan -
The Syrian Observatory for Human Rights, a Britain-based monitoring group, said Sunday that Kurdish forces had retaken from IS more than a third of the villages around Kobane, a strategic town on the Syrian-Turkish border.
The Kurds recaptured Kobane on January 26 after four months of fierce fighting backed by Syrian rebels and coalition air strikes.
But Jordan's Foreign Minister Nasser Judeh told ABC television that while the bombing campaign had "degraded" IS capability, the group was still in control of "vast territory".
Interior Minister Hussein Majali said in remarks published on Saturday that Kassasbeh's gruesome murder by IS was a "turning point" in the kingdom's fight against extremism.
As Jordan escalated its assault, IS claimed on Friday that an American aid worker it had taken hostage -- 26-year-old Kayla Jean Mueller -- had been buried alive under rubble by a coalition strike on its self-proclaimed capital of Raqa in Syria.
Mueller's parents said they were hopeful their daughter was still alive and appealed to IS to contact them in order to ensure her safe return.
On Sunday, US Secretary of Homeland Security Jeh Johnson said Washington was seeking clarification on Mueller's fate.
"We're learning as much as we can as quickly as we can about Ms. Mueller's situation," he told CNN. "Our thoughts, our prayers are with her family right now."