WASHINGTON – The fight between Islamic State and Western allies for the Syrian border city of Kobani intensified over the weekend, as Islamic State forces bore down on three sides and shelled Kurdish strongholds within.Eye witness reports indicate that municipality buildings, as well as a market place, were targeted. The group fired 44 shells, some of which hit Turkish territory, according to the Syrian Observatory for Human Rights.The US-led air coalition over Syria engaged in the battle by striking Islamic State targets around Kobani at least six times.With dozens of countries across Europe and the Middle East participating in strikes, the campaign has focused on Kobani more than any other city or asset, including Erbil and the Mosul Dam in Iraq at the launch of the campaign.Turkey, however, has yet to participate, a month into the battle over a city in its sights across the border.Ankara wants coalition partners to target the regime of Bashar Assad, the embattled president of Syria at the center of the civil war there that has killed over 200,000 people.After fighting intensified on Saturday, US President Barack Obama spoke with Turkish President Recep Tayyip Erdogan by phone on Sunday to discuss the battle and to strategize “steps that could be taken to counter [Islamic State] advances,” according to the White House.“The two leaders pledged to continue to work closely together to strengthen cooperation against [Islamic State],” the White House said in a readout.But the weekend was marked by a series of suicide attacks from Kobani to Baghdad, Iraq, where Islamic State first mastered the car bomb – or vehicle borne improvised explosive device – in its original incarnation as al-Qaida in Iraq in 2004.Two such car bombs were detonated in Kobani on Sunday, targeting Kurdish positions. The city is predominantly Kurd and has provided refuge to minorities across Syria fleeing the civil war there.And in Baghdad on Sunday, one suicide bomber killed 19 and wounded 28 others outside a Shi’ite mosque, where mourners were attending a funeral. Islamic State has not yet taken credit for the attack.But it comes among a marked spike in suicide bombings in Baghdad since a US-led coalition began bombing the group across Iraq and Syria last month. “The attacker approached the entrance of the mosque and blew himself up among the crowd,” one police officer said. The mosque is reportedly intact.Reuters contributed to this report.