China is increasingly using arms sales and trade as a diplomatic tool. Nothing unusual there, except that the Chinese are specializing in outcast, and outlaw, nations. This is risky business. For example. Chinese government and business officials are in accord that it's not practical to do any serious business with Venezuela because President Hugo Chavez has "a short attention span" and is likely to make glowing promises about all sorts of possible deals, but then never follow through.
Most other despots and dictators are more reliable. Thus China has been active in Africa, a dictators paradise, despite a post-Cold War enthusiasm for democracy there. If you have money, or a vote in the United Nations, China has guns, military trainers and business opportunities. No questions asked. Thus China has become a major arms supplier to Sudan, in return for a slice of Sudan's growing oil production, and investment opportunities in the local economy. At the other end of the scale is Zimbabwe, where president-for-life Robert Mugabe has trashed his own economy, but still has enough cash to pay for a planeload of guns from time to time. If a country is willing to dump diplomatic recognition of Taiwan, and recognize China instead, the favor will be repaid.
Russia used to own this segment of the market, but has generally acceded primacy to the Chinese. China is not out to police, or change the world. It's business.