U.S. aircraft have flown roughly 4,100 sorties in the air war against Islamic State militants in Iraq and Syria since August, including surveillance flights, refueling runs and bombing raids, a military officer said Monday.

The number of flights reflects the widening U.S.-led air campaign that began with a more narrowly-defined objective when it was launched by Washington on August 8. 

With the world on high alert over foreign fighters joining jihadist ranks in Syria and Iraq, Balkan states are launching efforts to clamp down on recruiting in their region, considered fertile ground by Islamists.

Of the more than 20 million people in southeast Europe, more than five million are Muslims, and an economic slump in weak states battered by past wars has fired up some of the disenfranchised.

Jordan, which has joined a U.S.-led coalition waging air strikes on the Islamic State group, said Sunday it has secured the country's borders against "any threat".

The government's statement follows warnings from analysts that Jordan was taking a risk by joining the U.S.-led coalition.

Already grappling with homegrown Islamists, Jordan has kicked the "hornet's nest" by joining the U.S.-led war on jihadists in neighboring Iraq and Syria, analysts say.

The Hashemite kingdom, a staunch ally of Washington, has sent warplanes to bomb the Islamic State (IS) militant group in Syria as part of a U.S.-Arab coalition.

Venezuela's leftist President Nicolas Maduro on Wednesday accused Western powers of helping create the jihadist crisis in the Middle East and said that the only solution involved respecting regional governments.

In his first speech to the U.N. General Assembly since succeeding the firebrand Hugo Chavez last year at the helm of the South American nation, Maduro said that the Ebola virus was the world's biggest threat but that Western powers were busy "bombing the people of Iraq and Syria."

By joining U.S.-led strikes in Syria, Gulf Arab monarchies are hoping to eliminate the threat to their authority from Islamic State jihadists and push the regime in Damascus out of power.

But their plan is not without serious risks, analysts warn.

Radical cleric Abu Qatada was acquitted of terrorism charges by a Jordanian court Wednesday and freed from jail, ending more than a decade of legal cases against the firebrand preacher.

Abu Qatada, who was deported from Britain last year, was found not guilty of conspiring to attack tourists in Jordan during millennium celebrations, due to insufficient evidence, officials said.

President Barack Obama will meet representatives of the five Middle Eastern nations that supported the first U.S. strikes in Syria later on Tuesday, his spokesman said.

Obama will see the officials from Saudi Arabia, Jordan, the UAE, Bahrain and Qatar after he arrives in New York for the United Nations General Assembly meetings, White House spokesman Josh Earnest told reporters on Air Force One.

In a landmark decision, a New York jury on Monday found the Jordan-based multinational Arab Bank liable on 24 counts of supporting terrorism by transferring funds to Hamas.

The jury deliberated for nearly two full days after a month-long trial at the eastern district court in Brooklyn that followed a federal law suit filed in 2004.

The United States and its Arab allies unleashed deadly bomb and missile strikes on jihadists in Syria on Tuesday, opening a new front in the battle against the Islamic State group.

Dozens of IS and Al-Qaida militants were reported to have been killed in the raids, which Washington said had partly targeted extremists plotting an "imminent attack" against the West.