China argued that it would no longer tolerate foreign naval vessels operating in international waters lying within its two-hundred-nautical-mile exclusive economic zone (an area granted by international law to waters surrounding sovereign territory, in which a country has rights to resources but no right to impede the passage of ships or aircraft) without express permission. This contravened the UN Convention on the Law of the Sea (UNCLOS), to which the PRC was an original signatory and which it ratified in 1996 (and which the US has not).
