Despite the Obama administration’s supposed openness to welcoming Syrians into the United States, it has quietly ramped up denials for Syrian visa applicants, closing America’s doors during a civil war that has killed almost a half a million people. Administration records reveal that Syrians are being refused temporary visas at a higher rate than applicants from any other nation of Syria’s size, and at a rate far higher than that for applicants from other war-torn nations in its region. Congress should investigate this troubling trend.

In 2010, the year before the conflict began, consular officers rejected only 28 percent of Syrian applicants for nonimmigrant visas that permit temporary stays in the United States for business or family reasons. The refusal rate has since doubled to 63.4 percent in 2015, twice the average refusal rate for Syria’s neighbors Iraq, Lebanon, Jordan and Turkey.

The U.S. embassy in Syria has been closed since February 2012, which means that Syrians seeking visas must leave the country. They are applying at posts throughout the region. From 2012 through 2015, roughly 60,000 Syrians left Syria, applied for visas and were rejected — four times the amount of refusals than during the prior three-year period from 2009 to 2011.

The State Department has not released the official grounds for the refusals, and when reached for comment, a State Department representative could not identify a specific cause for Syria’s higher rate of refusal, but mentioned the closure of the U.S. embassy and security issues.

While security concerns may justify some denials, there is a clearly disproportionate effect on Syrians compared to other war-torn countries. The Islamic State in Iraq and Syria (ISIS) is engaged in civil wars in both Iraq and Libya in addition to Syria, and the U.S. embassy in Libya is also closed. Yet in 2015, citizens of Iraq and Libya had refusal rates of only 52.8 percent and 43 percent, respectively — much less than for Syria.

Another motivation for the refusals may be that Syrians have difficulty proving “nonimmigrant intent,” which is a requirement that applicants prove they will return home after their visa expires. Consular officers have virtually unchecked authority to interpret the vague statute and deny visas. “Failure to establish entitlement to nonimmigrant status” was, by far, the top ground for visa refusals among all nationalities in 2014.

This leads to concerns that officers may be using Syria’s civil war against applicants, reasoning that they will never return to Syria. Yet statistics clearly indicate that there is no reason to anticipate an overstay crisis. A Department of Homeland Security (DHS) report released this year found that only 3 percent of Syrians overstayed their visas in 2015 — almost half the rate for Iraq and Libya (which, remember, still have higher visa approval rates).

Those Syrians who have overstayed may have requested asylum. Officers may fear that if more come, they will all apply for asylum. Justice Department and DHS statistics demonstrate that this belief is also unfounded. From 2010 to 2014, the U.S. granted visas to 53,000 Syrians, but just 6,220 have filed asylum cases — less than 12 cases per 100 Syrians admitted. So far, the U.S. has approved only 1,700.

Consider this: In fiscal year 2015, Syrians were never in the top 10 nationalities for U.S. asylum-seekers. By contrast, Iraq hit the top-10 four times. Whether the justification is war, overstays or asylees, Syrians are clearly being refused visas at much higher rates for reasons unrelated to factors unique to them.

It’s hard not to wonder whether consular refusals have been driven by instructions from supervisors or by political appointees in Washington to reject more Syrian applicants or, alternatively, to approve more Iraqis and Libyans than they would otherwise. Either possibility is consistent with the facts at hand.

Libyan and Iraqi refusals jumped after their respective civil wars but then leveled off (though the Iraqi rate jumped in 2015), while the Syrian rate has risen consistently year after year. If Syria’s visa refusal rate had risen at the same pace as Iraq’s since 2011, roughly 12,200 more Syrians would likely have been able to travel to the United States. If the rate had been the same as Libya’s, 17,800 would have come. Of these, 2,900 would have likely applied and ultimately received asylum.

This means that by disproportionately denying temporary visas to Syrians, the U.S. has rejected almost as many Syrians who were eligible for asylum as it has accepted through its refugee program. This outcome can only be described as a success if the government’s goal is to deny asylum to as many Syrians as possible — a goal seemingly at odds with the administration’s rhetoric.

Syrians with legitimate reasons to travel to the U.S. should not be refused based on an aversion to humanitarianism. Congress should investigate the dramatic increase in visa denials for Syrians, and the Obama administration should explain what steps it is taking to prevent unjust discrimination.

This post originally appeared in The Hill.