While fears are growing among world leaders that the Arab Spring is turning into an Arab Winter, David Cameron wanted to send a clear message that he is still a believer.
After meeting the leaders of Egypt and Libya earlier in the day, he addressed the UN General Assembly in New York with a wide-ranging speech about the Middle East.
A year after he told the same body that he welcomed the emergence of democratic movements across North Africa and the Middle East in the Arab Spring, Mr Cameron acknowledged that doubts were gaining ground in western capitals.
But he urged the international community to keep faith in the process of change in the Arab world, while accepting progress would be slow in some areas.
The murder of the US Ambassador Chris Stevens and the ongoing violence in Syria should spur the world on to complete the work he started, the Prime Minister said.
"One year on, some believe that the Arab Spring is in danger of becoming an Arab Winter," he told delegates.
"They point to the riots on the streets, Syria's descent into a bloody civil war, the frustration at the lack of economic progress and the emergence of newly elected Islamist-led governments across the region.
"But they are in danger of drawing the wrong conclusion.
"Today is not the time to turn back - but to keep the faith and redouble our support for open societies, and for people's demands for a job and a voice."
And while he understands concerns about the Islamist leaders coming to power, he said it is crucial that the process of democratic elections is respected.
His strongest language, however, was reserved for Syria.
The bloodshed in the country is a stain on the United Nations, he said, and in particular on those countries who have blocked action against President Assad - a clear swipe at Russia and China.
He pledged £8m in humanitarian assistance to the country, and called on the international community to do more.
Citing a recent Save the Children report documenting the torture and murder of children by regime forces in Syria, Mr Cameron told world leaders gathered at the UN headquarters: "The blood of these young children is a terrible stain on the reputation of this United Nations.
"And in particular, a stain on those who have failed to stand up to these atrocities and in some cases aided and abetted Assad's reign of terror.
"If the United Nations Charter is to have any value in the 21st century, we must now join together to support a rapid political transition."
But Mr Cameron has privately admitted that he is not hopeful of a political solution being found any time soon.
In his address to the UN, Mr Cameron also restated the UK's position that Iran should continue to face "the full force of sanctions and scrutiny from this United Nations until it gives up its ambitions to spread a nuclear shadow over the world".
The PM's 15-minute speech was heard in polite silence and received brief applause at the end.
Representatives of Syria, Russia and China remained in their seats throughout the address.