US-led air strikes on a Syrian border town killed "several hundred" Islamic State fighters but it may still fall, officials warned Wednesday, acknowledging significant jihadist gains in Iraq and Syria.
While Iraqi troops prevented the jihadists from seizing a lynchpin provincial capital near Baghdad, a senior US envoy admitted IS forces have scored important advances in Iraq,
John Allen, a retired four-star general and US envoy to the coalition fighting the Islamic State, said it would take time to build up local forces to defeat them there and in Syria.
In the border town of Kobane, Kurdish defenders backed by a flurry of US-led air strikes were reported to have stopped IS fighters from gaining ground and even recaptured some positions.
US Central Command said American aircraft carried out 18 raids near Kobane over two days, hitting 16 IS-occupied buildings.
In Iraq, government forces beat back an hours-long jihadist attack on Ramadi, capital of Anbar province.
But Allen warned that the group has made "substantial gains" and maintained the "tactical momentum."
President Barack Obama told military chiefs from more than 20 allies that they are facing a "long-term campaign" -- dubbed Operation Inherent Resolve on Wednesday -- against IS.
"There are not quick fixes involved. We're still at the early stages," Obama said after the talks in Washington.
Obama has expressed special concern for Kobane, which has become a symbolic battleground in the fight against IS, and about halting the IS advance in Iraq's western Anbar province.
- Clashes for Kobane HQ -
Fresh US-led strikes hit IS positions in Kobane on Wednesday, an AFP reporter across the border in Turkey said, and Syrian Kurds defending the town stood their ground against IS fighters.
Pentagon spokesman John Kirby said the strikes killed "several hundred ISIL fighters in and around Kobane" but that jihadists are pouring into the region and the town "could very well still fall."
The British-based Syrian Observatory for Human Rights said fighting was concentrated on the former Kurdish military headquarters in northern Kobane, which IS seized Friday.
It said Kurdish forces had retaken two nearby IS positions and pushed the jihadists from several streets to its west, but that IS fighters appeared in control of about half the town.
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NATO member Turkey has stationed troops, tanks and artillery along the border -- in some cases only a few hundred meters (yards) from the fighting -- but has not intervened.
It also has yet to allow US jets to mount attacks from its territory, and Turkish Foreign Minister Ahmet Davutoglu said only Syrian refugees could cross into Syria to defend Kobane, rejecting Western calls to open the frontier.
"We don't let Turkish citizens go into Syria because we don't want them to be a part of the conflict," he told reporters.
In Iraq, security personnel and tribesmen repelled a seven-hour assault on Ramadi.
IS jihadists attacked from three directions after hitting the city with mortar fire, police Captain Tahsin al-Dulaimi said.
The key town of Amriyat al-Fallujah, closer to the capital and one of the last parts of Anbar still holding out against the jihadists, also received reinforcements Wednesday from the Iraqi army.
Local forces warned on Tuesday the town was in serious danger, with its police chief saying that if Amriyat falls "the battle will move to the gates of Baghdad" and the holy Shiite city of Karbala.
Its fall would increase the danger to Baghdad, but IS fighters would still have to capture a significant stretch of government-controlled territory before reaching the capital.
"We do not believe that there is an imminent threat to the security of (Baghdad) right now," Kirby said.
Government forces have suffered a string of setbacks in Anbar in recent weeks, prompting some officials to warn that the entire province, which borders Jordan, Saudi Arabia and Baghdad province, could fall within days.
- Rising support for US troops -
Some officials in Anbar have argued anything short of an intervention by US ground forces would lead to it falling into jihadist hands.
Washington has ruled out sending troops back to Iraq to fight IS, but a poll published Wednesday showed a rising number of Americans think US ground forces are needed.
Forty-one percent of those surveyed believe the fight should include both air strikes and ground troops, up from 34 percent in September, according to the NBC News-Wall Street Journal poll.
IS has seized control of large parts of Syria and Iraq, declaring a "caliphate" in June and imposing its harsh interpretation of Islamic sharia law.
The group has committed widespread atrocities, including mass executions, torture and forcing women and children into slavery.