U.S. military commanders have been told to explore ways to increase security assistance to Lebanon and Iraq, the chairman of the Joint Chiefs said Wednesday, as the violence in Syria spills across borders and Iraqis face growing threats from the local al-Qaida offshoot.

Gen. Martin Dempsey said the assistance is aimed at improving the two nations' military capabilities and could include sending in U.S. training teams and accelerating foreign military sales of weapons and equipment to Iraq and Lebanon.

Jordan's King Abdullah II warned in an interview published on Wednesday against allowing Syria to fracture along sectarian lines, saying a Sunni-Shiite polarization "will have devastating consequences".

"A divided Syria means an open-ended conflict that would undermine the stability of the region and the future of its people for generations to come," the king, whose country is home to around 550,000 Syrian refugees, told London-based Asharq Alawsat Arabic daily.

Nearly 9,000 Syrian refugees staying in Jordan left the kingdom for home this month, bringing the number of returnees to more than 68,000 in the past two years, a government official said Tuesday.

"Some 8,974 Syrian refugees voluntarily returned to their country in June, mostly from the northern refugee camp of Zaatari," Anmar Hmud, the government spokesman for Syrian refugee affairs, told Agence France Presse.

Jordan on Saturday denied an American newspaper report saying that the CIA and U.S. special operations forces were training rebels from neighboring Syria on its territory.

"There is no training in our country whatsoever of Syrian opposition forces," Prime Minister Abdullah Nsur told a group of journalists including one from Agence France Presse.

About a dozen U.S. fighter jets will be flying and conducting training operations in Jordan, poised to respond if needed to protect allies if the war in neighboring Syria spills over the border, U.S. administration officials said Friday.

The increased show of U.S. military might — which brings the total number of U.S. forces in Jordan to as many as 1,000 — should be seen as a signal to Syria that it must confine its 2-year-old civil war within its borders, officials said. The officials said it is meant to show that the U.S. is committed to its defense relationship with Jordan and that America intends to maintain a strong presence in the region.

Members of Jordan's Muslim Brotherhood and youth groups were among 1,500 people who took to the streets of Amman on Friday to protest against Syrian President Bashar Assad and Hizbullah.

Demonstrators gathered outside the al-Husseini mosque after Friday prayers to protest against Assad and the Lebanese group which has sent fighters to bolster regime forces in Syria's bloody civil war.

Angelina Jolie said Thursday the Syrian civil war is the world's most acute humanitarian crisis and called on world leaders to make diplomatic efforts to end it succeed.

Jolie spoke at Jordan's largest camp for Syrian refugees, which she toured as special envoy for the United Nations refugee agency.

Belief that so-called honor killings are justified is still common among Jordanian teenagers, a Cambridge University study revealed on Thursday.

The study by researchers from the university's Institute of Criminology found that almost half of boys and one in five girls interviewed in the capital, Amman, believe that killing a daughter, sister or wife who has "dishonored" or shamed the family is justified.

U.S. and Jordanian F-16 fighter jets hit dummy targets in the kingdom's southern desert on Wednesday, while Navy SEALs and other special forces rescued "hostages" and nabbed "terrorists" in mock exercises under major multinational maneuvers.

Using live ammunition, six F-16s, two AV-8B Harrier jets, 28 tanks, 20 armored personnel carriers, 800 U.S. and Jordanian troops took part in a 45-minute drill in Quweira close to the Red Sea port of Aqaba as part of "Eager Lion 2013," which wraps up on Thursday.

Jordanian border guards killed on Wednesday a Syrian and wounded two others after they attacked Jordanian soldiers at the border while trying to enter the country, the army said.

While border guards have stopped Jordanians trying to slip into Syria to fight on several occasions, it is rare for Syrians to attack Jordanian troops.