Here's a closer look at the countries fighting the Islamic State and what they have to gain by banding together. (Davin Coburn/The Washington Post)

A proposal to create a protected buffer zone in Syria is worth study, the United States and two European allies said Wednesday as American-led airstrikes appeared to push back Islamic State fighters trying to overrun a border town.

The Western statements are a clear attempt at outreach to Turkey, which strongly backs carving out an internationally guarded territory as a possible condition to spending its powerful military over the border into Syria to help confront the Islamic State.

But it also could broaden tensions inside Syria. A buffer zone would likely bring a harsh response from Syrian President Bashar al-Assad — fearing it could become a haven for rebel factions fighting his government.

In Washington, Secretary of State John F. Kerry said the buffer zone concept is “worth looking at very, very closely” to stem the exodus of refugees into Turkey. More than 1.7 million Syrians have fled to Turkey to escape the country’s twin crises: a civil war since 2011 and the more recent advances by the Islamic State.

Britain, too, was “exploring” the idea, said British Foreign Secretary Philip Hammond, who held talks with Kerry. Earlier in Paris, French President Francois Hollande announced its support, according to a statement by his office.

Such a plan could have some similarities to the no-fly zone set up in northern Iraq in the 1990s to protect Iraqi Kurds from Saddam Hussein’s forces. But it’s unclear how it would halt the Islamic State, which has managed to encircle the Syrian border town of Kobane within sight of the Turkish border.

Intensified U.S.-led airstrikes forced the militants to give up some ground — a day after Turkey’s president, Recep Tayyip Erdogan, said the town was on the verge of falling into the militants’ hands.

The apparent retrenching by the Islamic State is unlikely to end its attempt to overrun the town, located in Syria’s Kurdish region. But the intensified airstrikes have given Kurdish militias a chance to bolster defenses and regroup after weeks of clashes.

Even while the airstrikes escalate around Kobane, Kerry stressed that Washington and its allies must not stray from the wider goals of trying to destroy the Islamic State’s lifeblood such as oil smuggling routes and supply lines.

“As horrific as it is to watch in real time what’s happening in Kobane, it’s also important to remember that you have to step back and understand the strategic objective,” Kerry said.

In Iraq, meanwhile, an official said Islamic State fighters used a shoulder-fired missile to bring down an Iraqi military helicopter, the Associated Press reported. The two pilots aboard were killed in the second such downing in a week near Beiji, the site of the country’s largest oil refinery about 130 miles north of Baghdad.

The battle for Kobane highlights many of huge challenges and deep political complexities in the confrontations against the Islamic State, which control wide areas of Iraq and Syria.

Gaining control of Kobane would be a propaganda boost for the Islamic State and show the limitations of airstrikes to halt its ground advances.

For the international coalition, Kobane underscores the internal frictions that complicate unity.

NATO-member Turkey has tanks and troops at the border, and authority from its parliament to intervene in Syria and Iraq. But Turkey has held back while it presses its demands, including the buffer zone and sharply boosting international support for Syrian rebels seeking to overthrow Assad.

Turkey and some key Western allies in the Arab world have joined the fight against the Islamic State but — in tandem — also are focused on bringing down Assad.

Gen. John Allen, a special envoy coordinating the fight against the Islamic State, is due to visit the Turkish capital Ankara Thursday. Kerry said a buffer zone would be on the agenda.

Rear Adm. John Kirby, Pentagon spokesman, said the buffer zone is not “on the table” of military planners at the moment. “That said,” he added, “it’s a topic of continued discussion.”

Journalists at the Turkish border could hear gunfire in Kobane on Wednesday. A Kobane envoy, Idris Nassan, told the Reuters news agency that Islamic State fighters had withdrawn from some positions inside the town.

Meanwhile, an attack believed carried out by Kurdish fighters destroyed a mosque minaret used by the Islamic State group as a lookout post, activists said, according to the AP.

At least six airstrikes were launched in the Kobane area since Tuesday as part of wider aerial attacks by warplanes and drones in Syria and Iraq, the U.S. Central Command said. More airstrikes were seen around Kobane on Wednesday.

In Iraq, the attack on the helicopter shows the capabilities of Islamic State fighters to target air power operating far lower than fighter jets. A Defense Ministry official told the AP that the Bell 407 helicopter was hit near the site where a Mi-35 chopper was brought down on Friday. Two people also were killed in last week’s attack.

In further pressures for Turkey, security forces in several areas clashed with Kurdish protesters demanding more help for fellow Kurds in Kobane. The unrest left at least 12 people dead and dozens injured, Turkish reports said.

The tensions threaten attempts by Turkey to ease a more than 30-year conflict with its Kurdish minority — part of a Kurdish heartland that includes parts of Iran and Syria. Turkey imposed curfews across its Kurdish-dominated southeast and deployed tanks onto the streets of Diyarbakir, the largest Kurdish city in the region.

Murphy and Morello reported from Washington.