In this new period of extreme heightened security, travelers entering the United States can expect increased scrutiny by immigration inspectors. Even before the new EOs heightened scrutiny at the borders, Customs and Border Patrol (CBP) officers had begun asking ESTA travelers for social media account information upon entry — the theory being that this will enable CBP and DHS to better spot individuals with ties to terrorist organizations. Though allegedly "optional," it is hard to believe that CBP will respect a traveler's refusal to provide account information. Visitors have already seen CBP look through their phones, laptops, and even make assumptions about their intentions based on business cards in their wallets. Additionally, it is unclear how the common social media practice of reposting from unverified sources will be handled.
If you are pulled aside for additional questioning, it does not automatically mean that you have done something wrong. It does mean that you should expect to be held up for a couple hours and to answer some intrusive questions, particularly in regards to your faith and political views. You are not required to answer such questions. You may be asked the same questions numerous times as well. Unfortunately, the Fourth Amendment search and seizure rights have very limited application at ports of entry (airports). Probable cause and reasonable suspicion are not required to initiate a search of your person or belongings. CBP officers can hold you for hours and search your belongings, including electronic devices.
Reports have circulated concerning green card holders being intimidated into signing documents that relinquish their lawful permanent resident (LPR) status. Officers at the border cannot, however, force LPRs to sign Form I-407, a document that automatically relinquishes status. Make sure you read every form placed before you and don't sign anything that you don't understand. You can request your attorney, but CBP is under no obligation to grant that request unless you are actually being charged with a criminal offense.
If you, as a visa holder, are perceived as being uncooperative, you can be denied entry. Permanent residents (green card holders) are in a gray area — their rights to due process exist but they can be detained as they await their removal hearing. U.S. citizens cannot be denied entry; however, there are reports of citizens originally from or having traveled to one of the seven targeted countries being held for long periods and having their Global Entry privileges revoked.