Does cyber security cross the line when crossing borders?

Potential visitors to the US were recently confronted with a new requirement on the long and complicated visa application form — to provide information about their social media identities.

Many shrugged off the addition, having long assumed that immigration authorities would in any case trawl through publicly available information. The US state department insisted the measures would enhance national security.

But some people, particularly within academia and civil society groups, expressed alarm. To them, it marked the latest in a series of invasive moves by governments to expand the use of technology to screen travellers, brushing aside privacy and safety concerns.