US President Barack Obama called Friday on Silicon Valley to put aside distrust of the government and become allies in defending cyberspace from terrorists, hackers and spies.

Obama's call came at a California summit, where he signed an executive order aimed at spurring better and faster sharing of cyber threats between the private sector and government.

"This has to be a shared mission," Obama said at a White House summit on cybersecurity at Stanford University, considered the birthplace of Google, Yahoo, and other technology titans.

"So much of our computer networks and critical infrastructure are in the private sector, which means government cannot do this alone. But the fact is that the private sector can't do it alone either, because it's government that often has the latest information on new threats."

He likened the Internet to the "wild, wild West" and said that the government was expected to be the sheriff.

Apple chief executive Tim Cook endorsed the effort as he addressed the packed conference prior to Obama.

Improving cybersecurity "is an enormous task, and no single company can accomplish it on its own," Cook said, while pressing the case for improved privacy protection as well.

"We believe we can bring about a future that fully embraces both privacy and security; we must get this right," Cook said.

- Sony, Snowden in focus -

The summit comes amid increased concerns over cybersecurity following a major intrusion last year into the network of Sony Pictures blamed on North Korea, and data breaches exposing the personal data of tens of millions of Americans.

Part of the reason the White House held the summit in Silicon Valley is to close a rift opened when a massive US online surveillance program was exposed by former National Security Agency contractor Edward Snowden.

Many tech firms and civil liberties activists have said they would back a cybersecurity plan only if accompanied by reforms of NSA surveillance.

"Grappling how government protects the American people from adverse events, while at the same time making sure that government itself is not abusing its capabilities, is hard," Obama said before signing the executive order.

"When people go online, we shouldn't have to forfeit the basic privacy we are entitled to as Americans."

During his remarks, Cook cautioned that history has shown sacrificing privacy can have dire consequences.

"Too many people do not feel free to practice their religion, or express their opinion or love who they choose," Cook said.

"In a world in which that information can make the difference between life and death, if those of us in positions of responsibility fail to do everything in our power to protect the right to privacy, we risk something far more valuable than money; we risk our way of life."

- Seeing classified info -

Rapid information sharing is considered an essential element of effective cybersecurity, because it enables companies to work together to respond to threats and thwart the spread of attacks.

Obama's executive order lays out a framework for expanded information sharing designed to help companies work together, and work with the federal government, to quickly identify and protect against cyber threats.

The new measure goes beyond a similar order signed by Obama last February, by allowing for cooperation between the Department of Homeland Security and private sector entities aimed at sharing data on threats.

It also makes it easier for private sector firms to gain access to classified threat information to step up cyber defenses.

In January, the White House made a renewed push for a new cybersecurity law, asking the new Congress to revive an initiative stalled over the past few years.

A White House statement said the order "paves the way for new legislation" by establishing a framework for private sector information sharing networks.

"Information sharing doesn't sound very threatening unless it is your information that others want to share," said Electronic Frontier Foundation senior staff attorney Lee Tien.

"The new executive order may encourage information sharing, but it's unclear whether it will further the public's interest in accountable information sharing or in the privacy of their personal information, given the roles of the intelligence and law enforcement communities."