As US Congress prepares for vote on whether to back military strikes against the Assad regime, John Kerry says Syrian leader Bashar al-Assad has "killed through his regime" and offers "words contradicted by facts".
On his side, Foreign Secretary William Hague has said he shares the same "revulsion at the utter callousness" of the regime.
Watch both politicians in the video below:
John Kerry on al-Assad's use of chemical weapons
William Hague on Syrian regime