U.S. planes pounded Islamic State (IS) positions in Syria for a second day on Wednesday, but the strikes did not seem to slow the militants' advance in a Kurdish area where fleeing refugees told of villages burnt and captives beheaded.
Syrian Kurds said IS had responded to U.S. attacks by intensifying its assault near the Turkish border in northern Syria, where 140,000 civilians have fled in recent days in the fastest exodus of the three-year civil war.
Washington, with the support of Arab allies killed scores of Islamic State fighters during the first day of air strikes, the first direct U.S. foray into Syria two weeks after Obama pledged to hit the group on both sides of the Iraq-Syria border.
However, the intensifying IS advances in northern Kurdish area underscored the difficulties Washington faces in defeating Islamist fighters in Syria, where it lacks strong military allies on the ground.
‘Network of death’
Still, speaking at the United Nations in New York Wednesday, President Barack Obama called on IS fighters to "leave the battlefield while you can,” and ruled any negotiations with the group as impossible.
"There can be no reasoning - no negotiation - with this brand of evil. The only language understood by killers like this is the language of force. So the United States of America will work with a broad coalition to dismantle this network of death," said Obama.
British Prime Minister David Cameron recalled parliament to vote on Friday on whether to join the air strikes. He said in an address at the U.N. that a comprehensive strategy was needed to combat Islamic State.
Separately, the U.S. said it was still assessing whether Mohsin al-Fadhli, a senior figure in the al-Qaeda-linked group Khorasan, had been killed in a U.S. strike in Syria.
A U.S. official earlier said Fadhli, an associate of al-Qaeda founder Osama bin Laden, was thought to have been killed in the first day of strikes on Syria. The Pentagon said any confirmation could take time.
Washington describes Khorasan as a separate group from IS, made up of al-Qaeda veterans planning attacks on the West from a base in Syria.
Fewer strikes, focus on ‘ISR’
Pentagon spokesman Colonel Steve Warren said Wednesday that the number of U.S. strikes has diminished, but stressed that the reduction in attacks should give no reason to believe the fight against terrorists in Syria is weakening. He said the U.S. military is now moving to collect more intelligence, surveillance and reconnaissance information, or “ISR.”
“I think you’ll see a mix of what we have seen in Iraq over the last several weeks, which is the result of active ISR, armed ISR, where we’ll strike targets of opportunity when presented," said Colonel Warren.
The Syrian Observatory for Human Rights monitoring group says bombings overnight hit Islamic State-held territory in Syria near the Turkish border, but the Pentagon told reporters the U.S. military did not conduct strikes in that area.
Colonel Warren also said that the military's intelligence shows U.S. strikes in Syria have not killed any civilians. This contradicts claims from the Syrian Network for Human Rights that about a dozen civilians died in the first night of strikes in the country.
The Syrian Observatory for Human Rights reports 120 militants belonging to the Islamic State and al-Qaida were killed in the first day of strikes.
The initial strikes in Syria included help from Bahrain, Saudi Arabia, Jordan, Qatar and the United Arab Emirates.
Netherlands to consider sending F-16s
The Dutch government on Wednesday will discuss contributing four F-16 fighter jets to the U.S.-led military operation against Islamic State, national news agency ANP reported.
A special cabinet meeting was called by the government of Prime Minister Mark Rutte for later Wednesday to consider what role the Netherlands should play in the air strikes against insurgents in Iraq and Syria.
The Netherlands was not among the nations approached by U.S. President Obama at a NATO meeting in Wales earlier this month, when he was building a coalition of allies against the hardline Islamic offshoot of al-Qaida.
The Dutch contribution had been on the agenda for a weekly cabinet meeting on Friday, but was brought forward in view of developments on the ground in Syria.
Dutch military participation would also have to be approved by the 150-seat parliament.
Nusra Front evacuates bases
Al-Qaida's Syrian affiliate, the Nusra Front, has evacuated its bases in populated areas of the Idlib region in northwest Syria after U.S.-led forces carried out air strikes on the group, its fighters said on Wednesday.
Another Syrian Islamist group, Ahrar al-Sham, has also ordered its followers to evacuate bases, according to the Syrian Observatory for Human Rights, a Britain-based monitoring group.
"Heavy weapons have been moved out of the bases. We do not want civilians to be harmed because of us,'' one Nusra fighter said in an online message posted on the Internet.
The Observatory also reported the Nusra withdrawal.
At least 50 fighters from the Nusra Front and eight civilians were killed in strikes by a U.S.-led coalition in Syria on Tuesday, the Observatory said.