U.S.-led airstrikes have struck
The strikes appeared to be the first time that the U.S.-led campaign in Syria had attacked
In the last week, U.S. aircraft began hitting Islamic State positions across Syria, while continuing to target the group in neighboring Iraq.
In a statement, U.S. Central Command said Saturday that aircraft destroyed an Islamic State building and two armored vehicles at the border crossing in Kobani. Kobani sits a few hundred yards south of barbed wire marking the Turkish border.
The strike was part of a series of attacks carried out across Syria on Friday and Saturday, Central Command said.
President Obama has pledged to "degrade and ultimately destroy" the Islamic State, also known by the acronyms ISIS or ISIL. In August, U.S. warplanes began airstrikes against Islamic State positions in Iraq.
Kobani has been the focus of a major battle pitting Syrian Kurdish militiamen against advancing forces of the Islamic State, an Al Qaeda breakaway faction that has seized huge stretches of territory in northern Syria and Iraq. The Kurds have called for help from the international community.
It was unclear whether U.S. aerial bombardment in support of the Kurds in Kobani was the start of a larger effort to aid fighters for the ethnic minority, who have been losing ground to the better-armed Sunni Arab extremist militants.
The conflict in Kobani is another indication of the complexity of the battlefield in Syria, where hundreds of factions have taken up arms.
The largely Kurdish district of Kobani and other Kurdish areas in northern Syria have been under semiautonomous Kurdish rule for the last two years. Arab Islamic fighters in Syria have vowed to destroy the Kurdish "gangs" and overrun Kurdish-held territory.
The U.S. acting as a de facto air force for the Kurdish fighters in northern Syria might draw apprehension in Turkey, a close American ally. The Turkish government, with a long history of conflict with its own Kurdish minority, has generally been hostile to the Kurdish fighters in northern Syria.
Syrian Kurds have accused Turkey of supporting the Islamic extremists in Syria, which Turkey denies.
But until Saturday the Pentagon had not confirmed that the U.S.-led air campaign had been involved in the battle raging in and around Kobani, one of the most active fronts in Syria. Both sides seek to maintain control of the strategic border crossing into Turkey.
The fighting in the Kobani area has prompted more than 130,000 people, mostly Syrian Kurds, to flee to Turkey since Sept. 19.
Extremists have seized many Kurdish villages, the Kurds say. Refugees positioned safely on the Turkish side have been able to watch some battles between Kurdish and Islamic State forces.
The secular Kurds and extremist Islamic State militants are archenemies. The two groups are squaring off in armed conflict across a broad front in northern Iraq, including the Kobani area.
The Syrian Kurdish militia, known as the Popular Protection Units, or YPG, after its Kurdish acronym, has been one of the most effective forces against a host of extremist rebel factions in Syria, including the Islamic State. The YPG says it is defending its Kurdish homeland, which it calls Rojava, and is not seeking expansion into largely Arab-populated zones of Syria.
The Kurds call the fight an effort to prevent the Islamic State from carrying out "ethnic cleansing" of traditional Kurdish lands.
Overall, the Pentagon said Saturday, fighter jets and remotely piloted drone aircraft conducted seven airstrikes Friday and Saturday on Islamic State positions across Syria, including the attack in Kobani.
The forces of three Arab countries—Saudi Arabia, Jordan and the United Arab Emirates—participated with the United States in some of the strikes, the Pentagon said without elaboration.
Journalists in the border area Saturday reported hearing fighter jets in the skies above Kobani.
Antigovernment activists in Syria said the strikes targeted the Islamic State's heavy weaponry and killed many extremist fighters, allowing the Kurds to advance. But there was no independent verification.
The involvement of the U.S.-led coalition on the side of the Kurdish militiamen in northern Syria is potentially significant.
The Kurdish force in Syria is a sister organization of the Kurdistan Workers' Party, a Turkish-based Kurdish militant group that has been at war with the Turkish government for three decades, though there has recently been a cease-fire. Both Ankara and Washington have designated the Kurdistan Workers' Party, known as the PKK, a terrorist group.
The Turkish government has called for Syrian President Bashar Assad to step down. Critics say Turkey's help has been vital for the growth of extremist groups in Syria, but officials in Ankara contend that they have only helped moderate Syrian rebels.
Since the Syrian civil war began in 2011, thousands of Syrian-bound volunteers from Europe, the Arab world and elsewhere have traversed Turkish territory en route to joining armed groups fighting to oust Assad's government. For years, Turkey did little to stop the flow across its lands.
But in recent months the movement of extremists via Turkey has caused alarm in Washington and European capitals. Many Syria-bound militants carry Western passports and can easily enter European nations and the United States after leaving Syria. Intelligence officials fear that Islamic militants returning from Syria could carry out terrorist attacks in the West.
Under pressure from Washington and European governments, Turkey says it has cracked down on the Syria-bound travelers. But broad swaths of the Turkish border still serve as rear-guard base for various Syrian factions fighting to oust Assad.