On the day after Christmas, three Chinese boats, one modified to carry four cannons, entered Japan’s territorial waters surrounding the Senkaku Islands in the southern portion of the East China Sea. The move, a dangerous escalation, is the first time the People’s Republic of China sent an armed vessel into an area that Tokyo claims as its own.

The sending of the three Chinese vessels on Dec. 26 appears to signal a new phase of incursions to grab not just the Senkaku Islands but the nearby—and far more important—Ryukyu Islands. Those include Okinawa, which hosts more than half of the 54,000 American military personnel in Japan, including those at Kadena Air Force Base, the Army’s Fort Buckner and Torii Station, eight Marine Corps camps, as well as Air Station Futenma and Yontan Airfield, and the Navy’s Fleet Activities Okinawa.

Geopolitically, Okinawa is key to the American-Japanese alliance and the heart of America’s military presence in Japan. But if Beijing gets its way, U.S. military bases will be off Okinawa soon. And Japan will be out of Okinawa, too.

Chinese authorities in the spring of 2013 brazenly challenged Japan’s sovereignty of the islands with a concerted campaign that included an article in a magazine associated with the Ministry of Foreign Affairs; a widely publicized commentary in People’s Daily, the Communist Party’s flagship newspaper and therefore China’s most authoritative publication; two pieces in the Global Times, the tabloid controlled by People’s Daily; an interview of Maj. Gen. Luo Yuan in the state-run China News Service; and a seminar held at prestigious Renmin University in Beijing.

At the same time, the Ministry of Foreign Affairs refused to affirm that China recognized Okinawa and the Ryukyus as Japanese.

The close timing of events indicated these efforts had been directed from the top of the Chinese political system.

Over the last decade, Beijing has been moving in on Okinawa step by step, almost island by island. It has regularly dispatched its ships and planes to the Senkaku Islands, often entering sovereign water and airspace, in a campaign to wrest from the Japanese those small and uninhabited specks in the ocean. The provocations around the islets, which China first claimed in 1971 and now calls the Diaoyus, spiked upward in 2012 and then noticeably declined the following year.

Whatever Beijing’s genuine intentions, Tokyo is not taking any chances. Japanese authorities are now fortifying 200 islands strung across the 870-mile gap between Kyushu, the most southern of Japan’s main islands, and the island of Taiwan.

When completed, the line of anti-ship and anti-aircraft missile batteries will dot the Ryukyu chain, blocking a critical passage linking the Chinese coast to the Western Pacific. Reuters notes that for the first time Japanese officials are publicly admitting that these fortifications are intended to keep China, in the words of the wire service, “at bay.”

As a result of the new barrier, the naval and air elements of China’s People’s Liberation Army will pay a dear price to get from the west side of the Ryukyus to the east in wartime.

Today, however, Chinese ships and planes can transit this line of islands unimpeded. Eleven Chinese military aircraft—eight H-6K bombers and three surveillance and electronic intelligence planes—did just that on Nov. 27.

The group split into two before reaching the Ryukyus, with at least four bombers flying through a critical chokepoint, the Miyako Strait, which cuts that island group in two.

The Japanese were obviously concerned.

After clearing the Miyako Strait, the H-6Ks flew 620 miles into the Pacific. From their turnaround point, the Chinese aircraft could have fired CJ-10K cruise missiles, which from there had the range to land conventional munitions—or nuclear warheads—on Guam, the American fortress in the Mariana Islands.

The H-6Ks, China’s most modern bomber, could also have launched their devastating payloads toward Hawaiian targets if they had proceeded deeper into the Pacific. And as Rick Fisher of the International Assessment and Strategy Center told The Daily Beast, China’s next-generation bombers, the H-10s, will be able to hit West Coast cities from locations over that body of water.

The most immediate U.S. concern, however, is that during their late-November jaunt the H-6Ks brushed by Okinawa, which sits on the north side of the Miyako Strait and is the biggest island in the Ryukyus.

Beijing’s argument, like all its territorial claims, is rooted in long-ago history—1372 to be exact. By that year, as Gen. Luo pointed out to the China News Service, the Ryukyu kingdom was paying tribute to the Chinese court, and Japan did not complete its annexation of the island chain until 1872.

In their landmark May 2013 People’s Daily commentary, Li Guoqiang and Zhang Haipeng of the Chinese Academy of Social Sciences maintained the annexation of the Ryukyus constituted an invasion. Moreover, they wrote that Japan’s defeat in World War II nullified the Treaty of Shimonoseki of 1895, by which the Qing court formally renounced its claims to the islands.

“For now, let’s not discuss whether they belong to China—they were certainly China’s tributary state,” said Luo to the China News Service. “I am not saying all former tributary states belong to China, but we can say with certainty that the Ryukyus do not belong to Japan.”

The issues are not as clear cut as Luo, Li, and Zhang indicate, however. A Japanese feudal lord conquered the islands in 1609 but permitted the Ryukyuans to also pay tribute to the court in China. Another complication undermining China’s position involves the identity of the Qing dynasty. Although Beijing now considers that set of rulers to be Chinese, the Qings did not think of themselves that way, especially during the early part of their rule, and the Chinese at the time certainly viewed them as foreign invaders.

Why, then, did Beijing question Japan’s sovereignty over the Ryukyu chain? It looks like it wanted to gain an advantage in the Senkaku dispute, as a May 2013 Global Times editorial, titled “Ryukyu Issue Offers Leverage to China,” makes explicit.

Yet Beijing’s position is ultimately puzzling because, by raising the stakes with intimidation tactics, the Chinese have made themselves look incurably aggressive, thereby reducing Japan’s incentive to agree to any territorial concessions. Once Beijing disputed more than just the Senkakus—in other words, once Chinese leaders showed their real intention was to dismember Japan—China essentially foreclosed further discussion.

“Using the Ryukyu sovereignty issue to resolve the Diaoyu dispute would destroy the basis of China-Japan relations,” Zhou Yongsheng of China Foreign Affairs University told the Financial Times. “If this was considered, it would basically be the prelude to military action.”

A fight of that sort is something China cannot win. As Dennis Blair, former commander in chief of the U.S. Pacific Command, said to The Daily Beast, “An attempt to take the Ryukyus by China would mean war with the United States, as we are pledged to defend Japan, and the Chinese would not succeed in capturing them.”

To win without fighting, the Chinese are doing their best to undermine Japanese rule. As June Teufel Dreyer, a political science professor at the University of Miami, told The Daily Beast, Beijing has been “quietly stoking the issue from time to time,” funneling cash to Chinese student associations in Okinawa. “Some funds may also find their way into support of Okinawans who are anti-U.S. bases,” noted Dreyer, who teaches courses on China and international relations.

These tactics, although irritating, are counterproductive, just enough to get Japanese policymakers angry but not enough to change the political calculus in the Ryukyus. Although the Ryukyuans may be irritated at Tokyo from time to time, they have no intention of becoming Chinese pawns, especially in light of Beijing’s military moves off their shores.

The issue going forward is whether Beijing will renew its Ryukyu campaign now that it is increasing the pressure on the Senkakus. One option for China is to go beyond the open-ended position it took in 2013 and lay a formal claim to the Ryukyus.

That would constitute another strategic mistake. “If the debate now includes Chinese extension of sovereignty over the Ryukyus, then this is precisely the kind of overreach that will ultimately harm China,” argues Toshi Yoshihara of the Naval War College, in an e-mail message to The Daily Beast. “This line of reasoning parallels China’s claims to ‘historic rights’ over the South China Sea.”

As Yoshihara notes, “Such a worldview suggests that everything is potentially up for grabs.” Chinese officials stopped talking about the strategically important Ryukyus around the same time they began to decrease their intrusions around the nearby Senkakus. After 2013, Beijing shifted its attention southward, to the South China Sea.

Now, Beijing’s ambitions are expanding in all directions. While making advances in the South China Sea, it is renewing efforts to take the Senkakus. Its next target looks like the Ryukyus, putting the American bases on Okinawa in play.

And China is unlikely to stop there. “Our navy wants to push through the island chains and reach the eastern Pacific,” said Zhang Haipeng, one of co-authors of the People’s Daily commentary on the Ryukyus, at the 2013 Renmin University seminar. The eastern Pacific, let’s remember, washes onto American shores.