Angola, the arena for a Cold War conflict between the United States and the Soviet Union, is now caught up in a new battle -- for its oil.

The West African state is now the continent's major producer, having eclipsed troubled Nigeria, and the Americans see it as a vital energy source in the years to come. So does China.

During the Cold War, the United States sought to depose the Soviet-backed rulers of the former Portuguese colony and supported their main foe, Jonas Savimbi, leader of the UNITA movement. The country's 27-year civil war ended in 2002.

Now Washington seeks to cozy up to Angola's president and wartime leader, Jose Dos Santos, who for three decades has headed a notoriously corrupt regime.

As with many other African states caught up in the oil boom, Angola's oil transactions and revenues, which account for 80 percent to 90 percent of export earnings, are kept secret through the state-owned oil corporation, Sonangol.

In recent years, China, which cares little about corruption or the excesses of dictatorial regimes, has engaged in massive investment in mineral-rich Africa to secure access to the raw materials it needs to feed its ever-expanding economy.

Beijing has provided more than $24 billion in loans to African states where its oil companies and industrial giants are operating, mainly providing infrastructure projects that are intended to improve the extraction and transportation of oil and other resources.

China is by far the leading buyer of Angolan oil, operating through Sonangol.

But the Americans, who for decades ignored Africa, are striving to catch up so they can get their hands on the vast new oil fields being found across West Africa and off its coast.

The U.S. presence has been enshrined in the newly established Africa Command, a military organization headquartered in Stuttgart, Germany, that many believe was created to extend U.S. military power on the continent to protect future oil supplies.

With the Middle East in constant turmoil, the Americans are dealing with regimes widely considered unsavory, such as that in Luanda, to secure access to the region's oil wealth.

That's been the name of the game for decades. But the relationship between the West and African dictators who are enriching themselves from the big-power stampede for their countries' oil may be changing.

How that might influence events is not clear. But a series of high-profile corruption trials in France, a consequence of President Nicolas Sarkozy's anti-graft drive, have already exposed the seamier side of Paris' dealings with African states, some of them former French colonies.

In October, an appeal court halted a judicial probe of palatial homes and other assets in France owned by the strongman presidents of three oil-producing states, Gabon, the Republic of Congo and Equatorial Guinea, who had been accused of pillaging their impoverished nations while holding power by force.

U.S. officials envision 25 percent to 30 percent of U.S. oil imports coming from Africa by 2015, up to a third more than the current level, primarily from Nigeria and Angola.

Khadija Sharife, a visiting scholar at the U.S. Center for Civil Society, wrote recently in Foreign Policy in Focus that Nigeria and Angola are "two primary beneficiaries of the African Growth and Opportunity Act, along with Chad, yet another petro-state government by lifetime dictator Idriss Deby. ...

"The United States is making other inroads in Angola in agriculture, economic reform and healthcare. One example includes Angola's partnership with USAID, which uses aid to promote U.S. multinationals like Chevron and technologies such as genetically modified organisms."

Now, the rivalry between China and the United States is becoming more complicated because the Luanda regime is being caught up in a dispute with two of its neighbors, the Democratic Republic of Congo and Congo-Brazzaville, over ownership of large offshore oil reserves.

The DRC has accused Angola, which helped it militarily during the 1998-2003 civil war in the Congo, of seizing part of the continental shelf claimed by Kinshasa. These zones are being drilled by U.S. giants Chevron Texaco and Exxon Mobil.

For its part, Congo-Brazzaville insists that two other blocks claimed by Angola and being drilled by BP of Britain and Total of France belong to it.