US Secretary of State John Kerry said Monday that the solution to the Syrian conflict must be political not military as Washington began a crucial week in its bid to persuade a skeptical public and Congress of the need for strikes.

US Secretary of State John Kerry said Monday that the solution to the Syrian conflict must be political not military as Washington began a crucial week in its bid to persuade a skeptical public and Congress of the need for strikes.

Kerry made an impassioned defense of President Barack Obama's push for action against Syria, saying that this was not the time for the world to fall "silent."

He made his plea in London before flying back to Washington to help Obama push his case for support from Congress and attempt to reverse his nation's mood.

After talks with British Foreign Secretary William Hague in London, Kerry said the US fully agreed that the solution to the conflict would come not from the battlefield, but from negotiations -- but the key was getting all the parties to talks.

"Let me be clear, the United States, President Obama, myself, others are in full agreement that the end of the conflict in Syria requires a political solution. There is no military solution, we have no illusions about that," Kerry said.

"A resolution will not be found on the battlefield, but at that negotiating table. But we have to get to that table."