Beirut - Syrian President Bashar Assad acknowledged on Wednesday what he said were recent "setbacks" in the war against insurgents trying to topple him, promising a comeback by his troops still entangled in heavy fighting.The rare admission of defeat follows opposition advances in northern and southern Syria that have punctured the notion that Assad is on his way to defeating the four-year-old rebellion. They also undermined Assad's claim of being a bulwark against the Islamic State group, which had eclipsed rebels over the past year.Wars have "ebb and flow, gains and losses and ups and downs", Assad said, speaking at a Damascus school to mark Martyrs Day."Everything fluctuates except one thing, which is faith in the soldier and his belief in ultimate victory," he said. "So when setbacks occur, it is our duty as a society to boost the morale of the soldier and not wait for him to raise ours."Government troops withdrew from the northern city of Idlib after it fell to opposition fighters in late March, followed by the strategic town of Jisr al-Shughour and the Qarmeed military base last week.His troops are now under fire at a few remaining outposts, including the national hospital in Jisr al-Shughour."God willing, the army will soon reach those heroes besieged in Jisr al-Shughour hospital to continue the battle to eradicate terrorism," he said.Activists reported continued intense fighting outside of the town.Meanwhile Wednesday, the Britain-based Syrian Observatory for Human Rights and a spokesman for Kurdish forces in the north-eastern city of Hassakeh said suspected Islamic State militants attacked a centre affiliated with the force and lobbed missiles at residential areas.Redor Khalil, a spokesman for the Kurdish People's Protection Units, or YPG, said a female Kurdish fighter, a civilian and four attackers were killed. Militants lobbed missiles at residential areas, he said.A Kurdish activist group, Yekiti Media, said at least four civilians were killed in one neighbourhood. The Observatory said 16 members of the Kurdish force were killed. Differing casualty figures are common after attacks.