The Electronic System for Travel Authorization (ESTA) is an automated system used by US Homeland Security to determine eligibility of visitors to enter the USA under the Visa Waiver Program. Citizens of 38 countries in the Americas, Europe and Asia are covered by the Visa Waiver Program. ESTA clearance is required to enter the USA by air.

A Social Media Information question was added to the ESTA application form in 2016. This question consists of a dropdown menu from which the applicant selects the applicable social media channels; then for each channel, the applicant is asked to supply the related username.

Here's the Customs & Border Protection explanation of the purpose of this question:

"Information found in social media will enhance the vetting process and may be used to review ESTA applications to validate legitimate travel, adjudicate VWP ineligibility waivers, and identify potential threats. If you choose to answer these questions and an initial vetting by CBP indicates possible information of concern or a need to further validate information, a highly trained CBP officer will have timely visibility of the publicly available information on those platforms, consistent with the privacy settings the applicant has chosen to adopt for those platforms, along with other information and tools CBP officers regularly use in the performance of their duties.

"For example, social media may be used to support or corroborate a traveler's application information, which will help facilitate legitimate travel by providing an additional means to adjudicate issues related to relevant questions about identity, occupation, previous travel, and other factors. It may also be used to identify potential deception or fraud. Social media may help distinguish individuals of additional concern from those individuals whose information substantiates their eligibility for travel.

"DHS will handle social media identifiers in the same manner as other information collected through ESTA..."

There are implied benefits and risks to answering this question. You might be able to avoid later questioning. Or something in your answer might raise a red flag. And NOT answering it might look suspicious in light of some of your answers to mandatory questions. So answering or not is a decision that requires a certain amount of consideration.

As has been the case since 2016, responding to this question is currently voluntary. But will it remain that way?

Privacy advocates are concerned that as Homeland Security ramps up its social media intelligence gathering in the face of global and domestic terrorism threats, the agency may be planning to make answering the Social Media Information question mandatory.

Is there already anything in your social media history that CBP might find objectionable? If so, it's probably too late to do anything about that.

But it might be prudent not to make any ill-considered posts from here on out.

For updates, watch this space.