Google said Tuesday it would offer stronger online security for "high risk" users who may be frequent targets of online attacks.
The US technology titan said anyone with a personal Google account can enroll in the new "advanced protection," while noting that it will require users to "trade off a bit of convenience" for extra security.
"We took this unusual step because there is an overlooked minority of our users that are at particularly high risk of targeted online attacks," said a Google security blog post.
"For example, these might be campaign staffers preparing for an upcoming election, journalists who need to protect the confidentiality of their sources, or people in abusive relationships seeking safety."
Google will require these users to log into their accounts with a physical USB key which will be part of two-factor authentication, to guard against fraudulent access.
"An attacker who doesn't have your security key is automatically blocked, even if they have your password," the statement said.
Google will provide additional monitoring for these accounts and limit access to sensitive applications, aiming to protect against impersonation and "phishing" to gain access to an account.
"Sometimes even the most careful and security-minded users are successfully attacked through phishing scams, especially if those phishing scams were individually targeted at the user in question," the company said.
Phishing is the use of deception to gain confidential information such as usernames, passwords, bank account details and credit card numbers.
In one of the most highly publicized phishing attacks, Hillary Clinton's campaign chairman John Podesta gave up his password to a hacker, resulting in a series of embarrassing leaks during the 2016 presidential race.