US fears over Syria military action
During the G20 summit in St Petersburg, Russia, US President Barack Obama repeated his belief that action is necessary following the use of chemical weapons in Syria.
The president added he was confident of persuading the public and politicians of the need to act, ahead of next week's vote in Congress.
However there are dissenting voices in the US.
The BBC's Mark Mardell has met one Republican Congressman in Ohio, who has doubts about voting in favour of a military response.
- From the section US & Canada