BEIJING - The United States' move to gain military supremacy in cyber space may trigger a new arms race, observers said.

"It has already had the lead in conventional military and nuclear forces. Now it is expanding this advantage to be the leading force in new fields, such as electromagnetic space and outer space," said Peng Guangqian, a Beijing-based strategist.

One week ago, US Secretary of Defense Robert Gates announced the inception of the world's first comprehensive, multi-service military cyber operation, called US Cyber Command (CYBERCOM).

The announcement came only a few days after President Barack Obama laid out his National Security Strategy, stressing for the first time in such a document the importance of cyber security as one of the core national security interests.

As early as 2005, the Pentagon recognized that cyber space was as important as land, ocean, air and outer space in the US National Defense Strategy, considering challenges in cyber space a "disruptive challenge", and saying they could "seriously endanger" US national security.

"The Department of Defense requires a command that possesses the required technical capability and remains focused on the integration of cyberspace operations," Gates wrote in his order to build such a command in 2009.

"Given our increasing dependency on cyberspace, this new command will bring together the resources of the department to address vulnerabilities and meet the ever-growing array of cyber threats to our military systems," said Gates.

Meng Xiangqing, a professor with the National Defense University, told China Radio International that there is a very thin line between a defensive and an offensive act when it comes to cyber space.

"CYBERCOM ranks high in the US military, reporting directly to the US Strategic Command, and the US is the most advanced state in cyber technology. This absolute advantage may trigger a new type of arms race," Meng said.

Despite the US insisting CYBERCOM is mainly defensive, Meng said it "has raised a new challenge for China, and that is how to guard our national cyber security."

States other than the US have already been planning mechanisms to guard national cyber security, including Britain, France, Russia, the Republic of Korea and Israel, which already has a military cyber force.

The potential enemy that CYBERCOM will fight has not yet been clearly identified.

"Our ability to predict where the threats are coming (from), even in conventional threats, is remarkably poor," said Deputy Defense Secretary William J. Lynn III.

"I think we need to be prepared for the unexpected," he added.

Lynn also said the threats to computer networks are "substantial".

"In fact, over the past several years we have experienced damaging penetrations."

Song Xiaojun, a Beijing-based military strategist, told Chinese newspaper World News Journal that even if other countries join in the cyber arms race, they are not capable of competing with the US since it possesses the core technologies of the Internet.

Of all 13 Internet root servers in the world, 10 are in the US, including the only one main root server, according to a report of State Council Information Office in March this year.

In his National Security Strategy, Obama stressed the importance of cyber security, describing it as "one of most serious national securities", urging the US to "deter, prevent, detect, defend against and quickly recover from cyber intrusions and attacks."

Obama listed nuclear proliferation and threats in outer space, together with cyber threats, as the most serious national security risks.