An IBM supercomputer has regained its place on the list of the world's fastest machines for the United States.
The IBM Sequoia took the number one spot on the Top 500 list, announced at the International Supercomputing Conference in Hamburg, Germany.
It is the first time a computer from the US can claim the top spot after China took first place in 2009.
The machine is capable of calculating in one hour what it would take 6.7 billion people around 320 years to manage with calculators. It is used at the US Department of Energy's Lawrence Livermore National Laboratory, in California.
It will be used to help simulate what will happen to nuclear weapons as they age
The machine is 1.55 times faster than Fujitsu's 'K Computer', which had headed the previous two lists.
The Sequoia uses 1.5 million processors - more than twice its nearest competitor - but actually uses less power, consming 7.9mw compared to the K's 12.6mw.
The researchers, who produce the list every six months, added that the new IBM machine is 273,930 times faster than the computer which led the list in 1993.
Elsewhere on the list IBM claimed five out of the top 10 places, but America's dominance actually fell overall, which its share of the fastest 10 computers falling from six to five.
The most powerful system in Europe is the German SuperMUC, and another German machine came in at number eight.
Italy also made its debut in the top 10 with an IBM BlueGene machine at CINECA. France also made it onto the top 10 list with its homegrown Bull computer. China has two sports on the top 10.
On the Top 500 list as a whole the UK has 25 machines - more than France (22) and Germany (20).