This is the reality of what Trump has done.
According to his executive order, the only people from Iraq, Syria, Iran, Libya, Somalia, Sudan and Yemen allowed into the United States at present are those with the following visas:
Diplomatic visas, North Atlantic Treaty Organization visas, C-2 visas (for foreign nationals traveling to the United Nations headquarters on official work), and G-1, G-2, G-3, and G-4 visas (for official representatives from foreign governments and international organizations).
What this means is that many people from these countries with other non-diplomatic visas (travel, student, work) – who have legitimate reasons to be in the United States, to live, work, and travel – cannot enter the United States right now.
Friends, family members, students, business people – all of them blocked it seems.
Additional info from the New York Times for people from these countries who are currently inside the US:
Legal residents who have a green card and are currently in the United States should meet with a consular officer before leaving the country, a White House official, who spoke on the condition of anonymity, told reporters. Officials did not clarify the criteria that would qualify someone for a waiver from the president’s executive order, which says only that one can be granted when it is “in the national interest.”
Sources:
Full text of executive order
The Guardian
New York Times
United States visa types
UPDATE: It is still unclear at present what the text “the Secretaries of State and Homeland Security may, on a case-by-case basis, and when in the national interest, issue visas or other immigration benefits to nationals of countries for which visas and benefits are otherwise blocked” (in subsection g) means and how it applies/affects people trying to get back into the United States on alternative visas.