In the wake of the attacks in Paris, at least 24 US governors have said that they want Syrian refugees barred from resettling in their states. What checks do Syrian refugees face before they enter the US?
After intense criticism that the United States was not doing its part to help with the migrant crisis afflicting Europe, the Obama administration announced in September that it wanted to resettle about 10,000 Syrian refugees in the US by the same time next year.
The decision was met with some fear that militants could exploit the refugee programme to gain entry into the US to carry out attacks.
After the attacks in Paris, which left 129 dead, and the news that one of the attackers may have entered Europe as a refugee, those fears have become amplified and spread to governors' mansions across the country as well as the corridors of Congress.
Newly elected Speaker of the US House of Representatives Paul Ryan has now called for a "pause" in the US refugee program. He tweeted, "Our nation has always been welcoming, but we can't let terrorists take advantage of our compassion."
The process for a Syrian refugee to resettle in the US is long and arduous, involving numerous federal agencies and intense background checks.
Compared to Europe, where fingerprints and simple information are taken and migrants can resettle with little difficulty, US processes look very different and are much stricter.
It is a long road for a Syrian refugee coming to the US - so where does it start?
Step 1: Leaving home & arrival at UNHCR refugee camp
As cities, town and villages have been overrun, millions of Syrian people have become displaced both internally and externally.
But to be eligible for permanent resettlement in another country, displaced persons have to leave Syria and find a camp run by the United Nations High Commissioner for Refugees (UNHCR), in a neighbouring country.
Many of these camps offer only the most basic living conditions.
Upon arrival at the camp, the displaced person registers as a refugee and is given the option to apply for resettlement.
Nothing is guaranteed at this point. Not every refugee will be referred by the UNHCR for resettlement.
Refugees are allowed to express an interest in particular countries, but the decision on resettlement is ultimately at the UNHCR's discretion.
Step 2: UNHCR referral for resettlement
The UNHCR then determines which refugees for whom resettlement makes sense, a senior administration official said.
Certain refugees get recommended to the programme in the US.
The State Department takes over after a referral is made from the UNHCR, and the Department of Homeland Security decides whether an individual application is approved.
Certain indicators for why a refugee may be recommended for the US programme include: if he or she has a relative in the US or whether it is likely he or she will be welcomed by a certain community.
"With Syrians, we've benefitted from years of experience in vetting Iraqi refugee applicants," one senior Obama administration official said. The screening is "robust since large-scale Iraqi processing in 2007."
Step 3: Vetting process with US begins
If a refugee is cleared to be considered by the US, the process for approval is lengthy - 18-24 months, said one senior administration official.
Refugees are admitted at about a 50% acceptance rate after being subjected to "the most rigorous screening of any traveller to the US," an official told reporters in a conference call.
That involves extensive in-person interviews about their experiences with conflict, as well as the collection of both biometric and biographic information that is cross-checked with the State Department, the Department of Homeland Security and in some cases, the Department of Defense.
Step 4: Resettlement
Ten thousand people have been referred for resettlement in the US, but the US has not processed their applications yet.
After 18-24 months, a refugee may then be sent to his or her new community.
The BBC spoke with one young man who resettled with his family outside of Louisville, Kentucky in September.
A local church organisation funded by the US government helped him land a job at a car factory. He wants to attend university in the US someday.
Like the organisation that helped this man, there are nine organisations that work with the federal government to place refugees across the US.