Several Chinese provinces and cities have increased restrictions in the hopes of meeting Beijing's zero-tolerance Covid target, among them the southern Chinese tech hub of Shenzhen.

Shenzhen, China's Silicon Valley, is carrying out mass testing after dozens of new local cases were recorded. Officials have suspended public transport and urged people to work at home this week as much as possible. White House press Secretary Jen Psaki said the Biden Administration was monitoring the lockdown of the tech hub "incredibly closely."

"What we're looking at is of course the impact on some of these ports around the impacted areas of China," she said.