China’s People’s Liberation ArmyNavy just reached a significant milestone in its efforts to develop a globally-capable “blue water” navy, as the nation’s second aircraft carrier entered service on Tuesday.

China’s new carrier, dubbed the Shandong, is not only China’s first home-built vessel of its type, it also earns the nation a place in the elite fraternity of countries boasting more than a single large flat-top. While there is some debate as to what qualifies as an aircraft carrier (the United States could arguably have as many as 24 depending on how loose your definition is) there are still only around six other nations on the planet that maintain more than one carrier in their fleets.

This second carrier, however, shares one significant weakness with its Soviet-built peer, China’s Liaoning: Neither vessel is nuclear powered. That means that, just like the rest of China’s Navy, these carriers are dramatically limited in their operational range. America’s Nimitz and Ford-class super carriers, for instance, run on nuclear power and can go for years between refueling. Of course, many of the vessels that travel in America’s carrier strike groups do still rely on diesel fuel for propulsion, but America’s vast network of military and otherwise friendly ports the globe over make blue water operations a fact of life for America’s Navy.

China’s Navy, and in turn its developing carrier strike groups, lack this global network of refueling points. This leaves China with no options but to conduct naval operations close to its own territory. That doesn’t stop China from cutting together pretty rockin’ propaganda videos though.

For now, however, that limitation is congruous with China’s immediate goal of securing the entirety of the South China Sea — a heavily contested waterway that is not only resource abundant and strategically valuable, but also sees around a third of all global commerce ship through it. China’s claims over the South China Sea, which it argues are based in ancient history, extend more than a thousand miles from its own shores and overlap internationally recognized claims of other Asian nations.

This map shows the extent of China’s new claims, over the waterway, in red, along with the competing claims of other nations within the region. As you can see, China’s claimed sovereignty over the South China Sea extends significantly south of its own borders. | Flickr

As a result of China’s aggressive behavior in the region, the United States and some allies have begun conducted Freedom of Navigation, or FONOP, voyages through China’s illegally claimed territory to demonstrate the international community’s unwillingness to recognize China’s disputed expansion.