All US visa applicants will now have to undergo social media screening.
The US State Department regulations said applicants will have to submit social media names and five years' worth of email addresses and phone numbers.
"National security is our top priority when adjudicating visa applications, and every prospective traveller and immigrant to the United States undergoes extensive security screening," it said in a statement.
"We are constantly working to find mechanisms to improve our screening processes to protect US citizens while supporting legitimate travel to the United States."
Certain diplomatic and official visa applicants will be excluded from the screening.
First proposed in March 2018, it's expected to affect about 15 million visitors.
Previously, it was applicable only to those applicants who needed additional vetting.
Qatar's prime minister said on Sunday that efforts to reach a new ceasefire in Gaza have made some progress but an agreement between Israel and Hamas to end the war remains elusive.
A huge blast most likely caused by the explosion of chemical materials killed at least 18 people and injured more than 700 on Saturday at Iran's biggest port, Bandar Abbas, Iranian state media reported.
The UN Refugee Agency (UNHCR) and the UN Office for the Coordination of Humanitarian Affairs (OCHA) have sounded the alarm over severe funding shortfalls that are hindering life-saving humanitarian aid in countries including Nigeria, Burundi, and Colombia.
A number of people were killed and multiple others were injured in Vancouver after a vehicle drove into a crowd at a Filipino street festival in the western Canadian city, police said on Saturday.