With the exception of Japanese dominance in the Pacific at the outset of World War II, the U.S. has ruled the seven seas since Teddy Roosevelt’s Great White Fleet circumnavigated the globe in the first decade of the 20th century. But that is slowly but surely changing as China’s first aircraft carrier undergoes sea trials and it moves to assert territorial claims in contested waters near the Philippines and Vietnam.

That is the reality behind President Obama’s visit to Darwin, Australia today where he will announce that the U.S. plans to use the remote northern city and its port as a new center of operations in Asia as it seeks to reassert itself in the region.

According to a report in The New York Times, the Darwin center is a first step to prove to its Asian allies that it intends to remain a crucial military and economic power in the region as the wars in Iraq and Afghanistan draw to a close.

The Darwin center will put American planes and ships closer to trading corridors in the South China Sea, where some traditional American allies worry that China is trying to flex its military muscle.

The more muscular approach toward China has far-reaching implications, not just geopolitically but also economically. With Republicans at home calling for punitive measures against China for its currency and trade practices, Obama needs to appear strong in pressing Beijing.

China has become the largest trading partner with Australia and most of the other countries in the region, undercutting American economic influence. It also is projecting military power more broadly than at any other time in modern history. Its true military budget is not made public, but experts say it has at least tripled over the past decade. It has shown off what appears to be new stealth aircraft and has bought advanced weapons from Russia.

The aircraft carrier (photo, above) is a former Soviet warship, which was formerly called the Varyag.

It is a relatively old design and was constructed in the 1980s for the navy of the USSR, but was never completed. When the Soviet Union collapsed in 1991, the rusting hull of the Varyag sat in dockyards in Ukraine until purchased by the Chinese government for conversion.

Experts note that while the carrier may be undergoing sea trials, it is years away from deployment.

The last time Darwin played a significant role in American military planning was during the early days of World War II, when Gen. Douglas MacArthur used the port as the base for his campaign to reclaim the Pacific from the Japanese.