President George W Bush is in Africa to launch HIV/Aids, development and anti-terrorism initiatives.
Angola: sub-Saharan Africa's No 2 oil producer
But his visit has also highlighted the growing importance of oil imports for the United States.
The US imports two thirds of its oil needs.
About 15% of that amount comes from West Africa and that figure is projected to rise to 25% in the next 10 years.
The oil sector in Sub-Saharan Africa is one of the fastest growing in the world.
Production has taken off in the Gulf of Guinea which includes Nigeria, Equatorial Guinea, Cameroon, Gabon, Angola and Congo.
By the end of 2003, hundreds of thousands of barrels of crude will be flowing from oil fields in Chad, through rain forests in Cameroon to tankers docked off the Atlantic coast.
An American company has secured a concession in the neighbouring Central African Republic.
In the aftermath of 11 September 2001, America is seen as looking to reduce its dependence on the Middle East by looking elsewhere for energy supplies.
Despite a reputation for political and economic instability, oil flows from Africa can be reliable, especially as production often takes place off-shore.
"Usually oil production takes place in enclaves, so continues regardless of what goes on around," said Douglas Mason, Africa specialist at the Economist Intelligence Unit.
"Political problems are much more localised in Africa."
US military involvement
America may even eventually increase its military presence in the region to secure its oil supplies.
Sao Tome - which has big oil reserves - has invited the US Navy to build a port from which to patrol the Gulf of Guinea.
But some analysts say investing in African oil reserves will not solve all America's energy problems.
"It is as well to diversify as much as possible. But no one oil source is more reliable than the other," says Robert Mabro, President of the Oxford Institute for Energy Studies.
"There is a move to reduce reliance on the Middle East but Africa also has its problems. Look at the recent strikes in Nigeria."
Professor of Petroleum and Economics at Dundee University, Paul Stevens describes as "mis-informed" officials in Washington who see African oil as crucially important to the US.
They want to reduce America's reliance on Saudi Arabia's goodwill, he says.
"It doesn't matter where you get it from, it's how much you pay. If oil cost $60 a barrel in the Middle East, it's still going to cost $60 in Africa.
"Africa and Russia are not going to replace Saudi Arabia which has excess capacity which can stabilise the market."