WASHINGTON D.C., USA – Cyber-attacks pose the "most serious economic and national security" challenge America faces, said Barack Obama.
The US President spelled out the scale of the threat in an opinion piece for the Wall Street Journal.
Foreign governments, crime gangs and individuals were probing America's net defences every day.
The US had to do more to put essential defences in place to avoid the debilitating effects of an attack.
"It would be the height of irresponsibility to leave a digital backdoor wide open to our cyber-adversaries," he wrote in the newspaper's editorial column.
Enemies struggling to defeat the US on the terrestrial battlefield may move the conflict to cyberspace, he warned.
Mr Obama rehearsed the potential consequences of a successful cyber-attack saying it could trigger a financial crisis if banks were hit. Health emergencies could be caused by infiltrating the computer systems in hospitals or water treatment plants. And, he said, taking out power plants could bring entire regions to a standstill.
"This is the future we have to avoid," he said, urging the US Congress to pass "comprehensive cybersecurity" legislation.
A revised version of the Cybersecurity Act of 2012 was introduced to the US Senate on 20 July. It seeks to create a council that will oversee the hardening of US infrastructure to make it less vulnerable to attack.
However, said President Obama, whatever measures America did adopt must contain strong measures to protect privacy and civil liberties.
"We have the opportunity - and the responsibility - to take action now and stay a step ahead of our adversaries," he wrote. "It's time to strengthen our defences against this growing danger."
Source: BBC News
