A Iraq War hero-turned-lawmaker challenged Secretary of Defense Jim Mattis on President Trump’s anti-refugee executive order, arguing that it makes it more dangerous for American troops abroad.

“We have American men and women in harm’s way right now who are working on troops and volunteers… standing shoulder-to-shoulder with them to fight our enemies, to fight ISIS,” Sen. Tammy Duckworth told The Daily Beast on Tuesday. “With this one executive order from the president, he’s put them in harm’s way. We just made Americans into more of a target than they already are abroad.”

Duckworth, a freshman Democrat recently elected to represent Illinois, has been advocating for green-card and visa holders who were detained at Chicago’s O’Hare International Airport in the immediate aftermath of the executive order last Friday afternoon. But she has heard next to nothing from the Trump administration.

“They need to come to Congress and explain the point behind this,” Duckworth said.

To that end, Duckworth is sending Mattis a letter Tuesday evening demanding information on how the executive order will affect the American military, including a security and risk assessment for U.S. personnel in the Middle East.

In the letter Duckworth argues that the order is dangerous because it sends the message that  “as an ally America cannot be counted on, cannot be trusted and is willing to compromise our values in turning our backs on Iraqis and Syrians fleeing religious and political oppression perpetrated by our shared enemies, such as ISIL.”

Duckworth also reminded Mattis of his comments, from six months ago, when asked about how a Muslim ban would affect U.S. foreign policy.

“This kind of thing is causing us great damage right now, and it’s sending shock waves through the international system,” Mattis said at the time.

—Tim Mak