President Barack Obama said for DAESH to be defeated, a Syrian agreement on a feasible political transition is a must.
"It's going to be a multiyear task and we're not going to be able to fully succeed in eliminating their safe havens until we have a political settlement of some sort in Syria," said Obama on Thursday, at an Asia-Pacific conference in the Philippines.
Obama also said further peace talks for Syria could identify certain opposition groups that can take part in the political transition.
But for now the US president identified the next step as a "ceasefire that may not be observed by everyone, but at least would create pockets of calm that could hopefully grow over time" and reiterated that the Syrian future have no place for the incumbent regime leader Bashar al Assad.
"It is unimaginable that you can stop the civil war there when the overwhelming majority of people in Syria consider him to be a brutal, murderous dictator."
"He cannot regain legitimacy."
Since the beginning of the four-year war in Syria, more than 250,000 Syrians have been killed, mainly by the Assad regime, whilst half of the country’s population is displaced internally or in the neighbouring countries such as Turkey, Lebanon, Egypt, and Iraq. More than 350,000 Syrians have also claimed asylum in Europe.
Russia and Iran have been keen allies to Assad throughout the conflict, providing him with logistical support, and most recently, Russia had started military air campaigns on Syrian lands.
Russia started launching air strikes in Syria on September 30 with the initial claim that it would be battling DAESH, signalling a new chapter in the Syrian conflict. However in time, Russia's intentions in Syria appeared only to be protecting the Bashar al Assad regime and its withering authority.
Obama said Russia and Iran have to decide whether to continue to prop up Assad or work with the international community to save the Syrian state.
"[World leaders] understand that this is not something that is distant, this ISIL (DAESH) group has aspirations to attack the entire civilized world," deputy national security adviser Ben Rhodes told reporters earlier Thursday. "So there is a new sense of urgency. We want to take that urgency and make it concrete."
Also Thursday, Saudi Arabia, a stringent critic of Assad’s regime that killed thousands of innocent civilians, announced it would hold a conference next month to try to unite the moderate Syrian opposition, no further details were given.