Vietnam's new cybersecurity law could force Alphabet Inc.'s Google and Facebook Inc. to choose between access to one of Asia's fastest-growing digital economies and protecting their users' privacy.

The law, which goes into effect Jan. 1 after the National Assembly passed it this month, requires foreign internet companies to store data within the country and open local offices. If requested, they'll also be required to hand over to the government the data of users suspected of anti-state activity — including spreading news that may impede Hanoi or hurt the economy.

The law mirrors efforts globally to safeguard domestic users' information and open up access to data that governments say they need to combat threats — what China refers to as its cybersovereignty. It also reflects a growing wariness about the influence of internet and social media giants that handle and parse information on and for billions around the world.