By Humeyra Pamuk
MURSITPINAR Turkey (Reuters) - Two days of heavy air strikes by U.S. warplanes have slowed an advance by Islamic State militants against Kurdish forces defending the Syrian border town of Kobani.
Turkish and U.S. officials said last week that Islamic State was on the verge of taking Kobani from its heavily outgunned Kurdish defenders, after seizing strategic points deep inside the town.
The tempo of coalition air strikes has increased dramatically, with U.S. fighter and bomber planes carrying out 14 raids against Islamic State targets near Kobani on Wednesday and Thursday, the U.S. military's Central Command said.
The strikes had seen the militants' advance slow, but "the security situation on the ground in Kobani remains tenuous," the U.S. statement added.
The four-week Islamic State assault has been seen as a test of U.S. President Barack Obama's air strike strategy, and Kurdish leaders say the town cannot survive without arms and ammunition reaching the defenders, something neighboring Turkey has so far refused to allow.
The State Department said on Thursday that a U.S. official had held direct talks for the first time last weekend with a Syrian Kurdish group involved in the fight against Islamic State in Syria, including Kobani. Kurdish spokesmen said their forces were giving coordinates of the militants' positions to the United States.
Islamic State has been keen to take the town to consolidate its position in northern Syria after seizing large amounts of territory in that country and in Iraq. A defeat in Kobani would be a major setback for the Islamists and a boost for Obama.
Heavy and light weapons fire were audible from across the border in Turkey on Thursday afternoon, with one stray mortar hitting Turkish soil close to abandoned tents, a Reuters correspondent said.
Turkish security forces moved civilians and media away from hills overlooking Kobani as the fighting raged.
Six air strikes hit eastern Kobani and there was fierce fighting between Kurdish and Islamist fighters overnight on Wednesday, but neither side made significant gains, according to the British-based Syrian Observatory for Human Rights.
Kurdish fighters later managed to seize a street in Kobani that had been held by militants, the Observatory said.
A journalist in Kobani said air strikes had allowed Kurdish forces to go on the offensive for the first time since Islamic State launched their assault four weeks ago.
"We walked past some (YPG) positions in the east yesterday that were held by IS only two days ago," Abdulrahman Gok told Reuters by telephone.
"Officials here say the air strikes are sufficient but ground action is needed to wipe out IS. YPG is perfectly capable of doing that, but more weapons are needed," he said, referring to the acronym for the Kurdish People's Protection Units.
Islamic State's Kobani offensive is one of several it has conducted after a series of lightning advances since June, which have sent shockwaves through the region and sparked alarm in Western capitals.
U.S. officials have ruled out sending troops to tackle the group, but Kurdish forces have been identified as viable partners for the coalition, and Kurds in Iraq have received western arms shipments to bolster their cause. No weapons or ammunition have reached Kobani, however, fighters there say.
Kurdish forces killed at least 20 Islamic State fighters on Wednesday west of Ras al-Ayn, another Syrian city on the border to the east of Kobani, the Observatory reported.
At least two YPG fighters were also killed during the clashes, in which Kurdish fighters seized Kalashnikovs, machine guns and other weaponry, The Observatory said.
The United States has been trying to persuade Turkey to take an active role in the campaign against Islamic State. U.S. and Turkish military officials held talks this week in Ankara to discuss details of what Turkey will do. A Pentagon spokesman said on Thursday they had gone "very, very well."
"The discussions were positive, we think ... our team's coming away with, I think, a general good report here, but I wouldn't get ahead of anything Turkey may or may not do," Rear Admiral John Kirby told reporters.
Turkey has refused to bow to pressure to aid Kobani, either by ordering in Turkish tanks and troops that line the border, or permitting weapons and ammunition to reach the town.
Ankara is reluctant to be sucked into the morass of the Syrian conflict without clear guarantees from Western allies that more will be done to help repatriate 1.6 million people who have fled across the border from Syria.
Officials are also wary of arming Kobani's Kurdish defenders, who have strong links with the militant Kurdistan Workers' Party (PKK), which has staged a decades-long insurgency against the Turkish government in the country's predominantly Kurdish southeast.
Turkish officials are increasingly frustrated with criticism of their actions toward Kobani, saying they have carried the humanitarian burden from the fighting, which saw 200,000 people cross the border from the Kobani area.
They also say air strikes fail to offer a comprehensive strategy against Islamic State, which has flourished in the power vacuum created by Syria's war. Ankara blames Syrian President Bashar al-Assad for this, and wants him toppled from power, something western allies currently refuse to countenance.
Speaking on Wednesday, Turkish Prime Minister Ahmet Davutoglu said Kurdish fighters who had fled into Turkey had been invited to return to Kobani to defend it, but had declined.
He also spelled out details for the "secure zones" that Turkey wants to be set up in Syria close to its border, so that refugees can begin to return.
Zones should be created near the city of Aleppo, which has seen some of the fiercest fighting of recent months. Others would be set up near the Turkish border in Idlib province, Hassaka, Jarablous and Kobani, Davutoglu said.
To boost legitimacy, the United Nations should enforce the zones, Davutoglu said, but failing that, the international coalition could provide the air cover needed.
"Turkey could provide all the help necessary if such protection zones are created. But when such protection zones do not exist, to ask Turkey to intervene on its own is to ask Turkey to shoulder this risk on its own."
Turkish officials are optimistic they can convince coalition partners to meet some of their demands, at which point Ankara would play a more active role, although it is unclear how long negotiations might take.
U.S. officials say creating safe zones is not a priority and NATO said last week it was not discussing such a move.
The Syrian Foreign Ministry on Wednesday reiterated Damascus' opposition to "buffer zones" - the phrase used by some Turkish officials - warning they would be a gross violation of international law, the Syrian state agency Sana reported.
(Additional reporting Seda Sezer and Dasha Afansieva in Istanbul, Oliver Holmes and Sylvia Westall in Beirut and Lesley Wroughton and David Alexander in Washington; Writing by Jonny Hogg; Editing by Giles Elgood, Peter Cooney and Ken Wills)