The Asia-Pacific region is anything but calm as China continues to flex muscle and agitate over its territorial claims in the East and South China seas.

In recent weeks, China has conducted naval drills at James Shoal, more than 1,000 miles from the Chinese mainland but just 50 miles from Malaysia, which claims sovereignty over it.

A Chinese marine surveillance plane intruded on Japanese air space near two islands in the East China Sea claimed by Japan and caused Japan to scramble jet aircraft. The incident coincided with ships of both countries shadowing each other off the Senkaku Islands.

"Despite our repeated warnings, Chinese government ships have entered our territorial waters for three days in a row," Japanese Chief Cabinet Secretary Osama Fujimura said. "It is extremely regrettable that, on top of that, an intrusion into our air space has been committed in this way."

China merely shrugged off the protest. The islands, it said, are Chinese territory.

The intrusions are a significant escalation in the dispute over the islands, analysts say. And an unintended incident could occur that could lead to use of arms.

Japan, obviously concerned that China could try to take the islands by force, recently met with U.S. military officials, sparking a sharp response from Beijing.

"No outside pressure will affect the resolve and determination of the Chinese government and people to maintain territorial sovereignty," it said.

The question remains: Why would China endanger relations with other countries in the region, where it recognized as a major power?

"I can tell you a lot of us are scratching our heads," said Dean Cheng, a research fellow at the Asian Studies Center of the Heritage Foundation in Washington. "I don't think anyone has that answer."

The same sentiment is expressed by diplomats and national security officials in the Philippines, which has its own dispute with China over islands, reefs and shoals in the Spratly Islands, which are along key maritime passages and believed rich in natural gas and possibly oil.

Chinese "visits" to the area and interference with Philippine fishing boats has led Manila to overcome nationalist sentiment and strengthen military ties with the United States.

Informed diplomatic sources said show-the-flag and supply replenishment visits to the country by U.S. ships were numbering about 100 per year but are increasing amid the tension. The Philippines has also purchased two former U.S. Coast Guard cutters for its paper-thin naval fleet.

Despite still-bitter memories of Japan's occupation of the Philippines in World War II, it has publicly supported political sentiment in Japan for removing its U.S.-imposed, post-war constitutional restrictions on Japan's military and its role and freedom to act.

"They (the Chinese) have only themselves to blame," said a Philippine national security official who requested anonymity. "Their aggressiveness is pushing countries in the region toward the U.S., countries that would normally be neutral in the complications between China and the U.S.

"What they don't realize is that they are creating a wall that doesn't keep the United States out of the region but keeps them in."

Diplomats and government officials in the Philippines and elsewhere speculate China's aggressiveness over the territorial disputes are the result of internal politics -- the rise of a new regime and the need to show its power --- and dysfunction between policy-makers in Beijing and policy-implementers, as well as nationalism.

"A situation has been created and they cannot reverse it because of domestic considerations," the Philippine official said. "Much of this has happened during the transition to new leadership in China and is in the case of a transition there is always a struggle between factions and factions don't want to be seen as weak and unable to defend China."

Cheng suggests something else is at play in China's behavior.

"I think a piece to this is a perception on the part of the Chinese that they are beleaguered without a corresponding understanding of why that is," he said. "I'm not really sure they really understand how their actions are perceived.

"China wants to manage how they are perceived but they want to do it by diktat."

Japan, the Philippines and Malaysia aren't the only Asian nations in dispute with China over island territories, Vietnam, Brunei, Taiwan and others are all part of the mix and claiming their rights under international law, which gives them dominion over territories with 200 miles of their coastlines. China has thwarted efforts for a collective diplomatic solution through the Association of Southeast Asian Nations and insists on bilateral talks.

"They are very big and strong and we are small and weak," the Philippine official said. "Bilateral talks would mean divide and conquer."

The Philippines has referred the dispute to the United Nations for mediation. China refuses to participate, let alone abide by any decision the U.N. panel would make.