South Koreans may have legitimate cause to disagree, but the nation in the east Asian region that has had the longest-term cause to build and maintain robust defenses against an unpredictable near neighbour is surely Taiwan.

The history of Taiwan — aka the Republic of China or RoC – is complicated, and the island state’s relations with its Communist neighbour have been just as labyrinthine. But since the early 1990s, when the Taiwan government formally dropped its rather quixotic policy goal of retaking control of the Chinese mainland, the status quo has been straightforward enough. The People’s Republic of China sees the island of Taiwan, and the other smaller islands the RoC controls, as natural parts of its state, and it is the PRC’s view, in the words of a 2010 national defense policy document, that “the two sides of the Taiwan Strait are destined to ultimate reunification in the course of the great rejuvenation of the Chinese nation.” Talk about an existential crisis.

Despite achieving recognition from only 21 nations – including the Vatican – Taiwan has established strong ties with most of the rest of the world. A key alliance is with the United States, which has become Taiwan’s key supplier of advanced defense systems. The relationship is ticklish – that same 2010 Chinese document says that the U.S. supply of weapons systems to the Taiwan government is “severely impeding Sino-U.S. relations and impairing the peaceful development of cross-Strait relations.”

So when Taiwan wants to buy, the U.S. does not always say sell. In 2011, a Taiwanese request to become an export customer for the F-35 fighter was denied. Even though there have been subsequent increases in tensions in the region – particularly those caused by the Chinese declaration of an air defense identification zone around the Senkaku islands, which are administered by Japan but also claimed both by the PRC and Taiwan – it is unlikely that this decision will be reversed.

“We sell F-35s via the foreign military sales process,” says Steve O’Bryan, F-35 business development VP at Lockheed Martin. “What that means is that the U.S. government is really selling the F-35. So we follow the U.S. government policy decisions.

“For the foreseeable future in that region, Japan, South Korea, Singapore and Australia are where the U.S. government is offering the F-35. And it will be the U.S. government that would authorize any changes to that.”