How difficult is it to get into the United States as a refugee? A lot more difficult than in most other countries, given our extensive security screening process. Every year, in keeping with our history as a nation of immigrants and refugees, the president works with Congress to decide on an annual quota of the world's most vulnerable refugees and asylum seekers, who will be admitted to the U.S. In 2016 the quota was 85,000; this year it is not yet clear what the quota will be. Not all of the quota is filled every year (it was not filled last year).

For all resettled refugees, the process begins when the United Nations refugee agency, a U.S. Embassy or an authorized NGO refers a refugee living outside his or her home country, usually in a refugee camp, to the U.S. Refugee Admissions Program, which is run by the State Department. Someone from a Resettlement Support Center then helps the refugee and his/her family (still in the camp) prepare their case file.

This process, which takes many months, involves gathering photos, checking the facts in the files and generally collecting evidence for the security clearance process. When complete, the case is presented to the Department of Homeland Security for adjudication. The refugee and his family are assigned a date for their interview with an officer of the U.S. Citizenship and Immigration Services (part of Homeland Security). This waiting period is the beginning of many months of vetting and screening that occurs while refugees are still in their country of first asylum.

These multiple security screenings and intensive background checks—by DHS, intelligence agencies, the State Department, and the FBI— can take 18 to 24 months. Once refugees receive conditional approval for resettlement, they are guided through a process of medical screenings, cultural orientation, sponsorship assurances, and referral to the International Organization for Migration for transportation to the United States.

In the U.S., the sponsoring agency places refugees with an official resettlement agency. The resettlement program has been in place since the 1980s and has resettled hundreds of thousands of refugees from all corners of the world. These agencies receive some federal assistance, but also depend on donations and state support to help the resettled refugees in their first year in the U.S. This assistance includes employment services provided to the refugees in their first 30-90 days.

The security screening process is stringent for all refugees, but even more so for those coming from countries such as Syria, Iraq and Afghanistan, whose refugees undergo an enhanced review process. Several federal agencies, including the National Counterterrorism Center and FBI, are involved, and the DHS officer who conducts the interview has specialized training for Syrian and Iraqi refugee cases. Security and criminal databases as well as biometric information are used, and background checks make sure applicants are who they say they are. The Syrian program has benefited from the administration's years of experience with vetting Iraqi refugee applicants, and the refugee screening process is constantly refined and updated.

The rigor and thoroughness of the vetting process has meant that of the 12,000 Syrian refugees admitted into the U.S. since the war in Syria broke out in 2011, most were only admitted last year. Processing resettlement applications is a slow and laborious task, in part because of the security screening.

The Syrian refugee screening process is not perfect — no screening can ever be — and the shambolic situation in Syria means there will be gaps in information. But the screening is a lot more rigorous and thorough for Syrian refugees than for other visitors coming to the U.S. By contrast, tourists and businessmen undergo very little screening. It makes one wonder why a terrorist would want to infiltrate the U.S. via the refugee resettlement process. Are Syrian refugees really the problem?

Karen Jacobsen is the Henry J. Leir Professor of Global Migration at the Fletcher School, at Tufts University. Thinking of submitting an op-ed to the Washington Examiner? Be sure to read our guidelines on submissions.