Story highlights People from nations under Trump's temporary ban will not be allowed into the US even if they are lawful permanent residents

The nations are all predominantly Muslim

Washington (CNN) The US government will not automatically allow green card holders who traveled to countries placed under a temporary travel ban back into the United States, two sources familiar with the matter told CNN.

Instead, after landing those travelers will have to apply for a waiver to the executive order that instituted the ban, the sources said. When they land, they will be taken into a secondary screening process in which they will be interviewed and their biometric and biographic information will be checked to see if there are any red flags. Then their eligibility to enter the country will be determined.

The countries targeted by Trump's executive order include the Muslim-majority nations of Iran, Iraq, Libya, Somalia, Syria, Sudan and Yemen.

Green card holders already overseas seeking to return to their homes in the US will be processed through a waiver authority that has already been established.

One official said there is a case-by-case admissions process and another said it is being done "expeditiously."