Vice President Biden was busy shuttling this week from Japan to China, trying to defuse tensions over a new air-defense zone that China has set up over disputed islands in the East China Sea.

To many observers, it may have appeared that China had overreached by unilaterally declaring the zone, and that Beijing had to back down when the United States and Japan continued to send in military flights without filing the flight plans that China demanded.

But, as described in a talk by Toshi Yoshihara, a U.S. Naval War College expert on China’s maritime strategy, China’s move is part of a calculated, incremental strategy. The goal: to exert naval and air dominance over much of the Pacific, replacing American primacy — and to get other countries in the region to recognize that dominance without a war.

Yoshihara’s lecture, sponsored by Philadelphia’s Foreign Policy Research Institute, was so fascinating that it’s worth a partial summary, especially since it reveals much about how China views itself and its future global role.

Everyone knows that China has become an economic superpower, but the country’s global ambitions are murkier. “Because China has such a huge stake, you would think they’d have an interest in maintaining an open commons,” says Yoshihara. However, he adds, “We don’t have a full grasp” of China’s ambitions or of what China wants to be when it rises to the heights of its power.

What we do know, he says, is that “the Chinese have been busy cranking out ships and submarines at a rate not expected 10 years ago.” A decade ago, experts pooh-poohed the idea that the Chinese would have a capable blue-water navy in the foreseeable future. But Beijing commissioned its first aircraft carrier in 2012.

There is a whole Chinese military-intellectual complex of scholars, analysts, and senior officers who passionately advocate the pursuit of sea power, on TV and in op-ed articles, playing on growing public nationalist sentiment by taking a strong stand against U.S. naval dominance in the region.

In part, this passion comes from China’s past, when it suffered many humiliations from seaborne invaders. Yoshihara quotes Wu Shengli, commander of China’s navy: “In China’s modern history, imperialists (Westerners) and colonists (the Japanese) initiated more than 470 invasions of China, including 84 large ones, from the sea.” Wu’s angst is evident, says Yoshihara. “He is saying ‘never again.'”

And in part the passion for sea dominance comes from Chinese geography. Chinese mariners can’t reach the high seas without passing through a series of choke points controlled by the United States or its allies. These choke points include a series of island chains, some hotly contested, that parallel China’s coastline and run from southern Japan to Taiwan to the Spratly archipelago.

This brings us back to Biden’s visit. The new air-defense zone that China established includes the air space above Japan’s Senkaku islands, which China claims and calls the Diaoyu islands. The Chinese zone also overlaps an air-defense zone established long ago by Japan. Not hard to imagine the potential for trouble there.

While technically an air-defense zone is only supposed to give the declaring nation the right to track and monitor flights for safety and security reasons, something else is going on here. Yoshihara says Beijing’s declaration is part of a Chinese “salami strategy.” By getting international pilots to file flight plans with Beijing before flying over the Senkaku islands, China is seeking “to confer legitimacy” on its claims over the East China Sea.

When he visited Tokyo, Biden made clear that the United States supports Japan’s claim to the islands, and that U.S. military planes will ignore the request for flight plans. But he didn’t demand that China rescind the zone, and U.S. officials don’t believe it would. Japanese officials, upset at the FAA’s quick acquiescence, held their tongues.

The real question at hand is China’s intentions. Yoshihara believes Beijing hopes to drive a wedge between Tokyo and Washington, while telling its own people that the United States is conceding China’s growing primacy in the region.

But the bigger question, he says, is China’s long-term aim. Does it accept free passage for all through the global common space, or will it try to exert control over the air and sea space around islands it is contesting with Japan, the Philippines, and others? The latter course would be extremely dangerous because the possibility for miscalculation is so high.