Former US Secretary of State Henry Kissinger has warned that President Obama could face the prospect of humiliation over Syria, if negotiations on Assad's chemical weaponry drag on too long and do not result in America's demands being met.
Speaking to Daybreak's Lucy Watson, he said President Obama's international reputation will rest on how he handles the crisis.
He said he supports the president's view on military action, as the use of chemical weapons is against international law, and an issue of global, not just national, significance.
As National Security Advisor and Secretary of State for Richard Nixon and his successor Gerald Ford, Kissinger pioneered of the US policy of detente with the Soviet Union, which led to the end of the Cold War.
He said it was vital for both the US and a Russia that they worked together as partners to solve the diplomatic deadlock that has enabled the crisis to escalate.
I think that Russia can have no interest to radicalise the Middle East, even more, and they need us, in a way, as partner.
He also praised Cameron for acting the best tradition of the "special relationship" the UK and the US enjoys.
A succession of British leaders have tried to balance the view they might have as individuals with what they thought was needed for the special relationship. I think Cameron has acted in the best tradition.