Olympic organisers are nervous after 16 policemen were killed by terrorists in the country's northwest.
Two men are accused of driving a truck at the officers who were jogging in the XinJiang region, before throwing home made explosives at their barracks and hacking at survivors with knifes.
It’s not yet clear who carried out the attack, but a number of armed Islamic groups had been fighting in the region for several years.
It’s all happened a long way from Beijing, but the fact that it happened this week has made Olympic organisers a little uneasy.