As Syria enters a fifth year of civil war, Secretary of State John Kerry said the United States will have to reach a deal with Syrian President Bashar al-Assad to enable a political transition of power and stop the crippling conflict that has left thousands of dead.
"We have to negotiate in the end," Kerry said in an interview broadcast on Sunday on CBS's Face the Nation, encouraging a diplomatic solution to the conflict in Syria.
"We're going to have to make it clear to (Assad) that there is a determination by everybody to seek that political outcome ... and I am convinced that, with the efforts of our allies and others, there will be increased pressure on Assad," he added.
Assad is under fierce domestic and international scrutiny, including allegations of human rights abuses.
Four years of civil war between government forces and rebel opposition groups, paired with the Islamic State militant onslaught in the north and east, has killed more than 200,000 Syrians, displaced millions more, and devastated the country's infrastructure.
Kerry did not specify during the interview what the terms of a potential deal with Assad could include.
A U.S.-backed attempt by the United Nations to mediate a truce between opposition groups and the Syrian government failed in 2014.
Damaged buildings are seen from a rebel-held area at the al-Amriya front line in Aleppo, March 3, 2015.
The country's civil war stems from a March 2011 uprising against four decades of rule by the Assad family that prompted heavy-handed retaliation from the state. Some cities, like Aleppo, are now divided between the two sides.
Washington and Damascus have separately taken on the fight against Islamic State militants, who gained a foothold in the fractured country last year and prompted nearly daily air raids from a U.S.-led coalition against Islamic State targets in the north and east.
In interviews with European media late last year, Assad said the air strikes were not helping counter Islamic State fighters and insisted ground troops were essential to defeating the militants.
Kerry has said that the air offensive has made a "significant impact" against the group.