Half a million refugees already inside the US will cost federal government more than $4 billion this year.

While much of the controversy surrounding America’s refugee resettlement program has focused on the security threat some refugees from terror hotspots may pose, little attention has been paid to the financial burden, borne by the taxpayer, of allowing in hundreds of thousands of migrants who are supported for years by the federal government.

According to data from a September, 2016 study by the National Academy of Sciences, Engineering, and Medicine, and a November, 2015 study by the Center for Immigration Studies, the roughly 519,000 refugees allowed into the United States since October 2009 will cost the federal government some $4.1 billion in 2017 alone, Breitbart News reported.

This figure does not include secondary costs borne by state and local governments, which, according to the National Academy of Sciences study totaled some $57.4 billion annually from 2011 to 2013.

The direct costs of resettlement will remain between $2-4 billion per year through at least 2022.

The above-listed costs do not include the expenses projected to be incurred by future refugees not yet in the country.