As if the mess in the Middle East and North Africa weren’t enough, Defense Secretary Leon Panetta arrives in Asia this week to confront a region that’s fast becoming a powder keg, fueled by power shifts, territorial disputes and lots of bad history.

The situation is likely to get worse — perhaps, much — before it gets better. Unfortunately, Team Obama’s promises of a strategic “pivot” to the Pacific may be seen in the region as being too little — and too late.

China’s rise, of course, is the source of some — OK, a lot — of the tensions. The ’hood understandably frets about Beijing’s military buildup: Growing at an average double-digit rate for more than two decades (11 percent in 2012), China’s defense budget is now the world’s second-largest.

More important: Beijing’s fielding platforms that pack plenty of power-projection punch — an aircraft carrier and stealth fighters as well as new destroyers and subs.

Meanwhile, a host of longstanding territorial disputes over islands — even rocky outcrops —are heating up, creating plenty of flash points in the East and South China Seas and Sea of Japan.

For instance, China, Taiwan and Japan all claim the East China Sea islands known in Tokyo as the Senkaku and the Daiyoutai in Beijing and Taipei.

Taiwan’s president recently flew to the islands to push its claims, while Tokyo plans to buy some of the islands from private owners , nationalizing them. Not to be outdone, China sent patrol ships to cruise the disputed islands.

In the South China Sea, China, Taiwan, Vietnam, the Philippines, Brunei and Malaysia also make competing claims to territories like the Spratly and Paracel Islands. The huge Chinese and Taiwanese claims actually encompass some 80 to 90 percent of the nearly 1.5 million square mile South China Sea, according to analysts.

Even Japan and South Korea, stalwart US allies, are getting into the act — with each other — in the Sea of Japan, squabbling over islands known as Takeshima (Tokyo) and Dokdo (Seoul), causing no shortage of headaches for the United States. (FYI, North Korea also claims the islands.)

China’s buildup and the competing claims (stoked by nationalism and unpleasant history) aren’t the only causes of tension; throw in growing global demands for natural resources, too.

For instance, some estimate the South China Sea seabed could hold more than 200 billion barrels of oil and nearly 900 trillion cubic feet of natural gas. (Plus, with world food prices rising, large stocks of fish.)

Some players may see the territories as worth fighting over. And China, Taiwan, Japan and South and North Korea all have modern militaries capable of creating one heck of a donnybrook should they so choose.

One other matter may be adding to increasing instability: nagging perceptions of waning American power in the Pacific — despite Team Obama’s plans for a diplomatic, economic and military pivot to the region.

In other words, after years of Pax Americana in the Pacific, for both friends and foes, there’s growing anxiety that America won’t (or can’t) lead — which would mean it’s pretty much every nation for itself.

Some in Beijing see Washington as firmly in decline, on track to be overtaken in the coming years by a rising China.

Our allies and friends also worry about our ability to fulfill a Pacific pivot while attending to interests elsewhere, like the Middle East. We’ve cut $500 billion already in defense — with another $500 billion on tap under sequestration.

The inconvenient truth is that if current trends persist, the Pacific will be anything but pacific, undermining important US interests. Worse: We may not be in a position to do much about it.

Peter Brookes is a Heritage Foundation senior fellow and a former deputy assistant secretary of defense.