Tehran, Feb 23, IRNA � While a possible cessation of hostilities in Syria is expected to take effect late in February, White House says a ceasefire in the war-ravaged country is difficult to achieve.

'This is going to be difficult to implement,' White House Spokesman Joh Earnest told reporters on Monday, according to AFP.

'We know that there are a lot of obstacles and there are sure to be some setbacks after all four years we've been trying to reach a diplomatic resolution to the many problems that plague that nation that has broken apart,' Earnest added.

'But this is a moment of opportunity, the White House official said, expressing hope that all parties help implement the agreement.

'We are going to continue to try to capitalize on this moment of opportunity, and we�re hopeful that the other signatories to the agreement will do the same thing,� Earnest said.

According to him, Barack Obama and his Russian counterpart President Vladimir Putin discussed over the phone ways to end the hostilities in Syria.

�President Obama did have an opportunity to telephone President Putin today. That call was placed at President Putin's requests and it was a call to discuss the ongoing conversations about arriving at an understanding around a cessation of hostilities in Syria,� he said.

Daesh and Nusra Front major terrorist groups are not going to be included in the proposed ceasefire.

'As announced in Munich a little over a week ago, this cessation of hostilities will apply to all parties in Syria except for ISIL (Daesh), except for al-Nusra and other terrorist groups that have been so designated by the UN Security Council,� Earnest said.

�In the coming days, the United States and our (International Syria Support Group) ISSG partners on the ceasefire task force will undertake a series of steps to implement the cessation of hostilities by February 27th,� he added.

Syria has been the scene of a foreign-backed militancy since March 2011.

A new report by the Syrian Center for Policy Research suggests that the conflict has claimed the lives of over 470,000 people.

By IRNA