President Donald Trump's administration has once again set the lowest cap on refugee admissions in the program's almost 40 year history, allowing fewer than 20,000 resettlements.

The administration will only propose resettlements for 18,000 of the 368,000 asylum and refugee applications it expects to field in the upcoming fiscal year, the Department of State said in a press release Thursday. The proposed number is a fraction of the 85,000 cap proposed by former president Barack Obama in 2016.

Trump's administration said it was focusing on "assisting refugees where they are concentrated" and cited the drain on American resources caused by illegal immigration.

"Indeed, it would be irresponsible for the United States to go abroad seeking large numbers of refugees to resettle when the humanitarian and security crisis along the southern border already imposes an extraordinary burden on the U.S. immigration system," the State Department said in its release.

Department of Homeland Security acting Secretary Kevin McAleenan also said that the proposed cap for the 2020 fiscal year would allow the department to address "the ongoing crisis at the southern border."

The Pentagon announced earlier this month it would use $3.6 billion in military construction funding to pay for Trump's long-promised wall at the southern border. Half of the money that was promised for the wall would come from planned international projects.

Trump's administration already dramatically cut the refugee cap for the 2019 fiscal year to 30,000, which was the lowest at that point in time.

Humanitarian organizations condemned the decision, saying it was cruel and driven more by ideology than any administrative or policy rationale.

"There is simply no justification for this abysmal number," a former State Department official with years of experience on refugee issues told NBC News. “The State Department has proven it has the capacity to bring in 30,000 this year, and nothing in the operational environment points to lowering the number next year."

The official also said the need is only greater — both for refugees left in limbo and for U.S. leadership — in addressing the global refugee crisis.

Refugee advocates said the reduction, combined with plans to set aside a certain number of slots for specific nationalities or applicants, meant thousands of people who have already passed security screening and were approved to resettle would be blocked from entering the U.S.

Jewish refugee advocacy group HIAS said in a statement that Trump was "playing to fear rather than showing strength."

"Refugee resettlement assures that at least some of those forced to flee their homes have a safe and legal pathway to refuge in the United States," HIAS president and chief executive Mark Hetfield said. "This administration has once again brought our country to a new low, by pledging to resettle fewer refugees than any other administration in history.”

David Miliband, president of the International Rescue Committee, said Thursday the announcement of the cap was a "sad day for America."

"Refugee resettlement is an essential lifeline that the U.S. provides for the most vulnerable refugees at a time of unprecedented global crisis," Miliband said. "Historic bipartisan support for this program — providing safety for persecuted people — has demonstrated U.S. values in action."

Miliband also implored Congress to pass the GRACE Act, which would set the annual minimum cap for refugees at 95,000 applicants.

"It is an unspeakable setback for refugee mothers who wish to see their children in school, parents who wish to work and support their family, and children who deserve a chance at life that isn’t solely defined by the instability and the trauma of their childhood," Miliband said.

The latest dramatic cut in refugee number marks a radical break with past Republican and Democratic administrations and another political victory for Trump’s senior adviser Stephen Miller, the architect of the president’s sweeping crackdown on immigration and refugee admissions.

Miller’s supporters tend not to distinguish between refugees — who are fleeing war and famine and go through elaborate vetting by the U.N. and U.S. authorities — and documented or undocumented immigrants.

Trump administration officials often suggest that the refugees pose a potential security risk. But former intelligence officials and experts studying refugee populations say there is no evidence to suggest refugees pose a heightened security risk.

Sources told NBC News last week that the Pentagon was in fact trying to fight against the slash to the refugee cap, insisting upon at least 6,000 spots be reserved for Iraqi applicants who worked for U.S. troops as interpreters or in other jobs.

Defense officials reportedly tried to make the case that accepting refugees is in the country's national security interest and that it provides a way to support allies who are inundated with refugees fleeing conflict and to promote stability in volatile areas.