SHARM EL-SHEIKH, Egypt — U.S. Secretary of State John Kerry said he would be willing to talk with Syrian President Bashar Assad to stem that nation’s violence.

In an interview with CBS News, Kerry said the U.S. is pushing for Assad to seriously discuss a transition strategy to quell the Arab country’s four-year civil war.

“We have to negotiate in the end,” Kerry said. “And what we’re pushing for is to get him to come and do that, and it may require that there be increased pressure on him of various kinds in order to do that. We’ve made it very clear to people that we are looking at increased steps that can help bring about that pressure.”

Kerry did not elaborate on what that additional pressure would be. There was no immediate reaction in Syrian state media to Kerry’s remarks.

Representatives of the Syrian government took part in talks in Moscow in January with opposition figures, although the main Western-backed opposition group shunned the conference.

The nearly four-year conflict has claimed over 220,000 lives, displaced a third of Syria’s population, and nurtured the extremist Islamic State group, which now holds a third of both Syria and neighboring Iraq in its self-declared caliphate.

Kerry said negotiations are important “because everybody agrees there is no military solution; there’s only a political solution. But to get the Assad regime to negotiate, we’re going to have to make it clear to him that there is a determination by everybody to seek that political outcome and change his calculation about negotiating. That’s underway right now.”

Kerry provided no additional details.

He spoke with CBS before leaving Egypt for Lausanne, where he was to resume negotiations with Iran on that country’s nuclear program.