The Olympics is a time primarily for sport and celebration, but diplomacy does not stop at the door of the UN, and for it to work it must be sustained and consistent.
That is why as the world comes together to celebrate the Olympics, we must not forget the plight of those who are trapped far away from the festivities.
Nor should we ignore the responsibility shared by some of those who have come to share in our celebration.
While Assad's actions have left the streets of cities and towns across Syria stained with blood, a dark cloud of blame still hangs over Moscow and Beijing.
Their decision to veto the UN Security Council Resolution on Syria didn't just put them on the wrong side of Arab opinion, it put them on the wrong side of history.
But this most recent diplomatic setback must not be an excuse for now giving up on international diplomacy.
The scale of the suffering in Syria means we must continue to press the Russians and Chinese to change course.
This week we host the Olympics.
Senior Russian and Chinese officials will be visiting the UK and are being invited to take part in official meetings and receptions.
Government ministers should use the opportunity to press the Chinese and Russian government's to change course.
Prime Minister Medvedev is attending the opening ceremony, and President Putin is reportedly visiting next week.
And when Chinese ministers met their British counterparts at Lancaster House - just a stone's throw from Downing Street - securing trade should have been on the agenda but I hope that stopping slaughter was too.
We must not miss this chance to press the Syrian people's case.
Russia and China have failed to live up to their responsibilities. As the United Kingdom hosts the Olympics, let's make sure we live up to ours.