What do you think is the reason behind tightening of immigration norms by US?

The recent change in immigration norms by US states that the applicants have to furnish and register their social media handles over a five-year period as per the recently released DS-160 and DS-260 forms. There is an exemption for diplomatic passports and other official visas. The change is brought upon to conduct an extreme vetting of foreigners who want to enter US as immigrants. The persons who will be impacted will include the green card holders and naturalised citizens. Almost all the Indians will be covered under the policy and a total of 14 million travellers to the US. The idea is to deny visa or not allow any person who poses a security threat to the nation. The policy has however, brought up questions like privacy, mass surveillance, gagging of free speech, etc. under limelight.