US President Barack Obama's senior counter-terrorism adviser has said the US faces "serious and significant" cyberthreats that could compromise national security.
Mr John Brennan says the administration is taking steps to improve cybersecurity and looking at the matter from an espionage and terrorism point of view.
He says national security is something that's at risk.
Mr Brennan isn't naming any country or individuals possibly behind cyberattacks. He was asked on NBC's "Meet the Press" about concerns that computer hackers in China have infiltrated computer networks.
AP