The CIA reported that Chinese companies continued, earlier this year, to work with Pakistan and Iran on ballistic missile projects. It is suspected that these same, or related, firms could provide assistance to Pakistani nuclear weapons programs. None of this is really political, as the Chinese companies are market driven and the Chinese government doesn't care much about how the money is earned. Chinese firms don't really care how their technology is used, and much of it is "dual use" (for peaceful applications or weapons).
Two Taiwanese intelligence officers, one of them retired, were arrested in Taiwan on charges of providing information to China. Both Taiwan and China have had some success getting each others intelligence officers to spy for them. Money is usually the major attraction.