The US President has banned Syrian refugees from entering the country to "keep radical Islamic terrorists out of the US".
Trump signed an executive order which also suspended the admission of refugees for four months, and stopped visitors coming from six mainly Muslim countries for three months.
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At a ceremony signing in Gen James Mattis as defence secretary, Trump said: "I'm establishing new vetting measures to keep radical Islamic terrorists out of the United States of America. We only want to admit those into our country who will support our country and love deeply our people."
A first draft of the order said the US would seek to create "safe zones" in Syria, but this was absent from the final order Trump signed at the Pentagon.
However, a mention of creating "safe zones" within Syria, seen in an earlier draft, was removed from the final order.
The order said new vetting policies would "evaluate the applicant's likelihood of becoming a positively contributing member of society."
The executive order authorises:
- A 120 day suspension of the US Refugee Admissions Programme
- A ban on Syrian refugees until the US makes "significant changes" to the vetting process
- A 90-day suspension on arrivals from Iraq, Syria, and "areas of concern" (reportedly Iran, Libya, Somalia, Sudan, and Yemen)
- Prioritising refugee applications on the basis of religious persecution (but only if the person is part of a minority religion in their home country)
- A cap of 50,000 refugees in 2017
The move follows an active first week for Trump, who also set in motion plans to build a wall on the border between the US and Mexico.