Relations between Cambodia and Thailand remain problematic. The Thai authorities continue to suspect Hun Sen of supporting a self-exiled former Thai prime minister, Thaksin Shinawatra, and the dispute over the territory surrounding the Preah Vihear temple on the Cambodian-Thai border has yet to be resolved. The stand-off at the temple in early February escalated into the most serious fighting yet as Cambodia and Thailand exchanged heavy artillery fire, and as a result thousands of civilians were displaced and an uncertain number of soldiers were killed or injured. The two countries also have yet to resolve the disputed sovereignty of resource-rich maritime areas in the Gulf of Thailand.

Rivalry between China and the US for influence in Cambodia is set to intensify in 2011-12. China has become an important partner for Hun Sen's government. It recently cancelled Cambodia's debt repayments falling due in 2010, in a move worth US$4.2m, as well as financing large-scale infrastructure projects. Unlike US assistance, which is typically conditional on greater respect for human rights, China's assistance has come without such strings attached. Cambodia's relations with Vietnam will be close while Hun Sen remains in power.