WASHINGTON/BEIRUT  - Declaring that the Islamic State militant group is a greater threat than Al-Qaeda, the Obama administration is considering military operations in Syria in a significant escalation of its weeks-long air strikes on the Islamic State militants in Iraq, according to US officials.

On Friday, the administration said that the killing of American journalist James Foley by IS militants amounts to a direct terrorist attack on the United States. President Barack Obama, who sought to build a legacy as a leader who ends wars rather than starts them, until now had resisted direct U.S. intervention in the more than 3-year-old Syrian civil war.

But shocked by the beheading of American journalist James Foley this week, US officials are looking at options including seeking congressional authorisation for military action against the Islamic State, The Washington Post reported Saturday.

A mandate from Congress could provide domestic legal justification for the unlimited use of force against the militant group across Iraq and Syria, a senior administration official said. Congress last formally authorized such action in 2001, against al-Qaeda and its associates, and 2002, against Iraq under Saddam Hussein.

The new authorization is one of several alternatives under active internal discussion as the administration grapples with whether and how to try to militarily defeat the Islamic State, which controls a wide swath of territory between Damascus and Baghdad, the Post said in a dispatch.

The -range of options- for direct use of the U.S. military includes temporary authority under the War Powers Resolution, constitutional authority for emergency action to protect U.S. citizens, and -having that discussion with Congress- about a more open-ended authorization to combat the Islamic State, the official said.

Obama has ordered airstrikes in Iraq under the first option, good for 60 days until early October. The second option was used this summer to launch a failed rescue attempt of American hostages held by the Islamic State in Syria.

 The third would entail a debate with an uncertain outcome among lawmakers with widely divergent views on presidential powers and overseas military action.

The official did not rule out the immediate use of airstrikes or other action in Syria if necessary to protect U.S. citizens. The recent military raid, which was unsuccessful in locating four hostages, was followed by this week’s videotaped beheading of one of the captives, journalist Foley.

-If you come after Americans, we are going to come after you,- deputy national security adviser Benjamin Rhodes told reporters Friday. -We’re not going to be restricted by borders.- Foley’s execution -represents a terrorist attack against our country,- Rhodes said. The administration believes that it provides international legal justification for military action under self-defence doctrines.

While contingency plans for broader airstrikes in Syria have been prepared for presidential review should Obama ask for them, so far he has not, according to the newspaper. Nor has the intelligence community drawn up a list of high-value targets among individual Islamic State leaders, as it did with al-Qaeda, the senior official said.

 -We’re obviously trying to find them,- the official said. But -we haven’t made a decision- on whether to target individuals. The official spoke on the condition of anonymity to discuss closed-door policymaking and intelligence matters. While it formulates a more comprehensive, long-term policy, the official said, the administration is focused on driving the extremists out of Iraq and containing them in Syria. The Iraq policy is -a convergence of U.S. airstrikes, more arms and training- for Iraqi and Kurdish forces, and persuading Sunni communities to reject the militants, the official said. -There are going to be gaps to fill- in that strategy, -and that’s what we are looking at now,- the official said. Islamic State forces advanced into Iraq from Syria in the spring, quickly capturing the northern city of Mosul and rapidly moving south to within 60 miles of Baghdad.

While the administration sent additional assistance to the Iraqi military, it used the promise of still more aid as leverage to force a change in Iraq’s government. Moreover, at least 14 militants were killed and 150 wounded in overnight clashes with Syrian troops defending an air base in Raqa province, a monitoring group said on Saturday.

The clashes came as the Islamic State group launched a new bid to capture the Tabqa base, the government’s last bastion in the northern province, the rest of which is in the hands of the militants.

The Syrian Observatory for Human Rights said the attack began overnight when a suicide bomber blew himself up at the entrance to the base. The two sides then exchanged rocket, artillery and heavy machine gun fire and the army deployed air strikes against the attacking militants, the Britain-based group said.

The air raids continued into the morning, with eight strikes against the town of Tabqa that killed 13 people, among them an additional 10 IS fighters. Those deaths brought IS losses since it began its assault on Tabqa to at least 94, with more than 400 wounded, according to the Observatory.

IS has brought in reinforcements from other areas it controls in Syria, as well as neighbouring Iraq, the Observatory added. The assault on Tabqa comes after IS seized the army’s Brigade 93 and Division 17 posts in Raqa, killing dozens of soldiers, some whom it beheaded. The army has airlifted reinforcements to the base and stepped up air strikes against IS positions across Raqa, using both precision rockets and barrel bombs. Moreover, The jihadist Al-Nusra Front has posted a video showing kidnapped Lebanese security personnel calling on the Hezbollah movement to withdraw its fighters from Syria.

The nine men - apparently eight policemen and a soldier - are among 24 security forces still in the hands of militants after fighting erupted on the Syrian border earlier this month. In the video posted Friday night on Islamist websites, the men are seated in front of a black flag with the logo of Al-Nusra, the Syrian affiliate of Al-Qaeda.

Although the men say they are speaking freely, they use the language of Al-Nusra and other Sunni Muslim extremist groups in referring to the Shiite movement Hezbollah, which means -Party of God,- as the -Party of Satan.-

They call on their family members to stage demonstrations and block roads in Lebanon to protest Hezbollah’s involvement in Syria, where the Shiite group is fighting alongside the regime to put down a Sunni-dominated uprising. One of them says the hostages have been warned they will be killed unless their families take action.

The men have been held hostage since an unprecedented outbreak of violence between militants and the Lebanese army in the Arsal region that began on August 2. The fighting erupted after soldiers arrested a Syrian jihadist, prompting extremists to open fire on army positions and storm a police station.

Several days of fighting in the area, which lies on the Syrian border, killed 19 soldiers, 16 civilians and dozens of militants. It ended with a truce negotiated by Lebanese Sunni clerics, but the militants withdrew from the area taking their hostages with them. The clerics who negotiated the truce had been seeking the release of the hostages, but they announced in a statement on Friday that they were suspending their mediation efforts.

They said the decision was taken -to allow other parties that are more able to deal with this issue.- Lebanon’s As-Safir newspaper said Saturday that the governments of Turkey and Qatar were now involved in negotiations to free the security forces. The fighting in Arsal was the most serious border incident since the Syrian conflict began in March 2011.

The war has regularly spilled over into Lebanon, and raised tensions between Sunnis who back the uprising and Shiites who mostly side with President Bashar al-Assad. Hezbollah says it is fighting in Syria to prevent extremists from entering Lebanon, and the group dispatched thousands of fighters to Syria’s Qalamun in particular, just across the border from Arsal.

The group’s fighters helped regime forces recapture most of Qalamun earlier this year, with opposition fighters taking refuge in mountains along the border. The Syrian Observatory for Human Rights, a Britain-based monitoring group, said Saturday that fierce clashes between Hezbollah and rebel groups including Al-Nusra erupted overnight. At least 14 people were killed in the fighting, the Observatory said, including 10 members of Islamist rebel brigades. Syrian warplanes also carried out five air raids on areas along the border with Lebanon, it said.