Acting Attorney General Sally Yates ordered the Justice Department not to defend President Trump’s executive order on immigration and refugees in court.

Yates, a veteran of the department who was appointed by former President Obama, sent a letter Monday to officials in the department laying out her orders, the New York Times first reported. Shortly after, she was removed from the post by Trump.

The extraordinary move by Yates comes at a time when Trump's immigration order, released late Friday, is reverberating across the government. More than 100 officials in the State Department have reportedly signed onto a draft memo protesting the policy, drawing a rebuke Monday from the White House.

Yates -- while she was still acting attorney general -- said the Department of Justice would not present arguments in defense of the Executive Order unless and until she becomes convinced that it is appropriate to do so.

"My responsibility is to ensure that the position of the Department of Justice is not only legally defensible, but is informed by our best view of what the law is after consideration of all the facts. In addition, I am responsible for ensuring that the positions we take in court remain consistent with this institution’s solemn obligation to always seek justice and stand for what is right," she wrote.a

"At present, I am not convinced that the defense of the Executive Order is consistent with these responsibilities nor am I convinced that the Executive Order is lawful."

About an hour after the news of Yates's decision broke, Trump tweeted that Democrats were obstructing him and referred to an "Obama AG."