As the situation in Syria continues to deteriorate, the regime of Bashar al-Assad has found two steadfast allies: Russia and the People’s Republic of China (PRC).

While Russian interest in Syria may be rooted in the longstanding ties between Moscow and Damascus (and the substantial amount of arms that Syria has purchased over the years from Russian arms manufacturers), China’s interest is less clear. Syrian armories are not filled with Chinese weapons. Syria–PRC trade is only about $2.2 billion and mostly involves Chinese exports to Syria; Syria is not a major oil producer, and most of the 100,000 barrels per day it produces is shipped to Europe.

Yet Syria clearly has significance for the PRC. Since assuming its seat on the U.N. Security Council in 1972, China has cast only eight vetoes. Of these, two have been in opposition to proposed sanctions on Syria—in October 2011 and again this month.

Some have suggested that the Chinese veto is cast not in support of Assad’s regime but as part of a Sino–Russian effort to balance the United States. Yet Beijing’s reaction today to U.S. Secretary of State Hillary Clinton’s condemnation of the veto suggests that perhaps more is at work here. Rejecting Clinton’s description of the veto as “despicable,” the Chinese foreign ministry in turn declared her comments “totally unacceptable,” while People’s Daily described the U.S. as “super arrogant.”

The Chinese leadership has long opposed interference in the “internal affairs” of other states. This is partly rooted in China’s unhappy history with imperialism, but it also provides a cover for their own crackdowns on Tibetans and Uighurs. In this context, the application of sanctions has increasingly been seen as an initial step toward eventual regime change, whether in Iraq or Libya. This is potentially exacerbated by concern over whether the Arab Spring, which saw the overthrow of various authoritarian regimes, might not have a Chinese sequel—an especially pointed concern as the Chinese leadership prepares for political transition this fall.

Chinese opposition to the imposition of sanctions, then, is likely as much due to concerns about Chinese vulnerability and fears about internal stability, now and in the future, as it is concern about the Syrian population. The vehemence of the Chinese response to Clinton’s remarks suggests that the leadership’s fears may be closer to the surface than generally recognized.