President Obama recently issued an executive order calling for the US to build the world's most powerful computer by 2025.

The computer currently occupying the top spot, Tianhe-2, is located in Guangzhou, China. And, with a computing speed of 33.86 petaflop per second, it has been in the pole position since 2011. A petaflop is a measure of how fast a computer can perform - one petaflop per second is one thousand trillion operations, carried out in a second.

Obama, however, wants the US to build a machine that would be 30 times faster than the Chinese computer. It would be able to perform one quintillion (a billion billion) calculations per second - a figure which is known as one exaflop - and aid the US in conducting scientific research and performing complex simulations.

Developing the world's fastest supercomputer also helps the US to pioneer new technology and retain the country's technological edge against foreign rivals like China.

Lewis: 'Calling for the fastest supercomputer is a symbolic way to make up for a lack of attention to science'

In a DW interview, James Lewis, director of the Strategic Technologies Program at the Washington-based Center for Strategic and International Studies (CSIS) and US President Barack Obama's former cyber security advisor, says the race for the greatest supercomputer is just about prestige, given that it is the number of supercomputers a country has and the way they are put into use that really matters.

DW: What constitutes a supercomputer and what are these machines capable of doing?

James Lewis: Supercomputers are specialized, high performance computers used for research. They have different architectures, components and software than the computer on your desk.

There's something called distributed supercomputing that links hundreds of desktop machines together (you can download a program for this from NASA for free), but what we are talking about here are highly specialized machines that are often custom made.

What have governments or states used these machines for?

Super computers have both civil and military uses, for medicine, weather prediction, earthquake prediction, design, aerodynamics, and cryptography. They're research tools. The US and China also use them for nuclear weapons design.

Are there any risks or drawbacks involved in having such computers?

You don't hear of supercomputers being hacked. It's easier to just steal the results. They also have specialized requirements for cooling, but they really don't pose any risk.

How would you assess China's current computing capabilities as compared to those of the United States?

The US has more supercomputers, China has the fastest. In overall computing power, the US leads, but China went after the prestige of being in first place. There's something called the Top 500 List - it has been around for at least 20 years - that shows who has what and inadvertently creates a sense that there is a race.

Since 2013, China has boasted the world's fastest computer, the Tianhe-2. What is China capable of doing with this machine?

It could do advanced design, including weapons design, and code breaking. The Chinese say they do scientific research, which is probably true, but they probably also do military research.

President Obama recently issued an executive order creating the National Strategic Computing Initiative (NSCI), with the goal of researching and building the first supercomputer to reach 1,000 pentaflops (or one exaflop). What are the advantages of such a machine and why does the US seem so keen to compete with China on this field?

The US hasn't had a coherent science policy in years, particularly for physical sciences like computing. The focus has been on politically motivated topics and "boutique" issues. There are also battles for Federal money within the scientific community. The supercomputer ruling reflects these trends. Calling for the fastest supercomputer is a symbolic way to make up for a lack of attention to science.

Obama wants the US to build the world's most powerful supercomputer

Is China currently planning an even faster supercomputer and why is it so important for a country to have the world's fastest computer?

This is just a contest for prestige, and kind of silly. The Chinese lusted after the top spot for years, solely to say they had the biggest. And now that they've got it, the US appears to be annoyed. It is how many supercomputers you have and how you use them that makes a difference, not having one really fast computer.

How does Obama's decision play into the ongoing cyber-espionage accusations between the countries?

Supercomputers can help build better weapons and break secret codes. So they are a tool in the growing military competition between the two countries.

James Lewis is director of the Strategic Technologies Program at the Washington-based Center for Strategic and International Studies (CSIS) and US President Barack Obama's former cyber security advisor.