President Barack Obama has arrived in California to hold a summit on cybersecurity.

Fresh from the Sony hacking scandal and other hi-tech attacks, the US leader wants to encourage firms to share more data about cyber threats with the government and each other.

He is set to sign an executive order with that aim in mind. On Tuesday, the White House announced a new intelligence unit to coordinate analysis of cyberthreats.

But Silicon Valley giants are reluctant to fully support legislation requiring information sharing.

They want to see reforms to government surveillance practices exposed by former National Security Agency contractor Edward Snowden.

The recent attack on Sony Pictures has been described as “a game changer” by a senior White House official.

Hackers stole data, debilitated computers and pressured the studio to halt release of a satirical film about North Korean leader Kim Jong-un. The FBI took the unusual step of accusing Pyongyang of being responsible.

Friday