President Barack Obama has ruled out deploying US ground troops in Syria and says military efforts alone cannot solve the country's problems.
"It would be a mistake for the United States, or Great Britain... to send in ground troops and overthrow the [Bashar] Assad regime," he told the BBC.
He also said he did not think so-called Daesh would be defeated in his last nine months of office.
But he said: "We can slowly shrink the environment in which they operate."