Speaking at a press conference in London on Monday, Kerry said a military strike on Syria would be “unbelievably small.”

The secretary of State emphasized that there would be no U.S. troops on the ground in Syria, and he insisted the U.S. action could limit Syrian President Bashar Assad's ability to use chemical weapons in the future.

“We will be able to hold Bashar al-Assad accountable without engaging in troops on the ground or any other prolonged kind of effort in a very limited, very targeted, short-term effort that degrades his capacity to deliver chemical weapons without assuming responsibility for Syria's civil war,” Kerry said. “That is exactly what we are talking about doing – unbelievably small, limited kind of effort.”

McCain, the most prominent advocate in Congress for a military response to Assad, has threatened to pull his support for a U.S. strike in Syria if it isn’t extensive enough.