Kurdish fighters are holding off the advance of Islamic State militants in Kobani, Syria, but heavy fighting is continuing for control of the city near the Turkey border.
The U.S. military command said its fighter jets, along with those from Saudi Arabia and the United Arab Emirates, conducted four airstrikes Saturday and Sunday in Kobani, destroying one of the insurgents' fighting positions and a staging area.
The British-based Syrian Observatory for Human Rights said the jihadists were sustaining heavy casualties in the fighting.
United Nations Secretary-General Ban Ki-moon said "thousands of live are at stake" in the fighting for control of Kobani. He called on the warring sides "to prevent a massacre and protect civilians."
Dark plumes of smoke could be seen rising above the city Sunday as Kurdish fighters battled to defend the city from the continuing onslaught by Islamic State extremists.
Turkish troops remain disengaged just across the border, despite increasingly vocal international pressure on Turkish President Recep Tayyip Erdogan to intervene.
U.N. officials in the region have warned that as many as 12,000 Kurds, including hundreds of elderly people in the city's center, "will most likely be massacred" if Kobani falls.
The British-based Syrian Observatory for Human Rights says Islamic State extremists controlled 40 percent of the town by early Saturday.
The Turkish government has so far refused to join the battle, citing ties between Kobani's Kurdish defenders and the outlawed Kurdistan Workers Party.
The PKK has waged a decades-long rebellion for self-rule in southeastern Turkey and has been designated a terrorist organization by Ankara and Washington.
Addressing Turkey's reluctance to help Syrian Kurd fighters, U.S. Defense Secretary Chuck Hagel said Saturday that Washington is making "considerable progress" in talks with Ankara on plans to train moderate Syrian fighters.
Hagel, speaking in the Chilean capital, said U.S. talks in the coming days with Turkish military officials will focus on specifics of Turkey's training commitments.
Hagel added that the situation in Kobani is difficult and complicated. But he said Iraqi security forces are in full control of Baghdad and continue to strengthen their positions there.
Hold Iraq, Syria ground
Islamic State fighters also control large swaths of nearby northern and western Iraq, where a local council leader (Sabah Al-Karhout) told CNN the situation is "very bad."
He said the council has intelligence that the Islamic State group has sent at as many as 10,000 reinforcements to the outskirts of Baghdad from Syria and from the Iraqi city of Mosul in the north.
Separately, coalition forces over the weekend conducted five airstrikes against the Islamic State group in Iraq, using attack and remotely piloted aircraft.
Airstrikes in Syria were conducted by the U.S. as well as Saudi Arabia and the United Arab Emirates forces. In Iraq, the U.S. and United Kingdom conducted the airstrikes.