WASHINGTON President Donald Trump signed an executive order Friday that bans Syrians from taking refuge in the United States, halts the U.S. refugee resettlement program for four months and temporarily blocks people from a handful of unnamed countries from entering the U.S. at all.

I am establishing new vetting measures to keep radical Islamic terrorists out of the United States of America. We dont want them here, he said at a swearing-in ceremony at the Pentagon for Secretary of Defense James Mattis. We dont want to admit into our country the very threats we are fighting overseas.

Trump approved the refugee ban amid the biggest refugee crisis in history and on Holocaust Remembrance Day, which honors the millions of people killed during World War II , many of whom tried to flee to the U.S. but were turned away .

Its not the blanket ban on Muslims that Trump advocated for during his campaign, and it does not single out any country by name other than Syria for its refugees.

But Trump did say earlier in the day that he would prioritize helping Syrian Christians . He also mentioned radical Islamic terrorists while signing it. And in the text, it carves out an exception for admitting refugees who are religious minorities even while nearly all others will be barred for 120 days.

Heres what the order will do, with immediate effect:

• Block refugee admissions from the war-torn country of Syria indefinitely.

• Suspend refugee admissions from all countries for 120 days. During that period, the government can accept refugees on a case-by-case basis, but only in the following scenarios: if they are a religious minority facing religious persecution, if the U.S. must admit the person to meet an international agreement, or if they are already in transit and denying admission would cause undue hardship. After that period, the U.S. will only accept refugees from countries jointly approved by the Department of Homeland Security, the State Department and the Director of National Intelligence.

• Cap total refugee admissions for fiscal year 2017 at 50,000 less than half of the 110,000 proposed by the Obama administration.

• Ban for 90 days all immigrant and nonimmigrant entry of individuals from countries referred to in section 217(a)(12) of the INA, 8 U.S.C. 1187(a)(12).

• Suspend visa issuance to countries of particular concern. After 60 days, DHS, the State Department and DNI are instructed to draft a list of countries that dont comply with requests for information. Foreign nationals from those countries will be banned from entering the U.S.

• Expedite the completion of a biometric entry-exit tracking system for all visitors to the U.S. and require in-person interviews for all individuals seeking a nonimmigrant visa.

• Suspend the visa interview waiver program indefinitely and review whether existing reciprocity agreements are reciprocal in practice.