WASHINGTON (AP) — Customs and Border Protection was caught off-guard by President Donald Trump’s travel ban despite being the entity responsible for implementing it, the Department of Homeland Security’s inspector general said.

In letters sent Monday to members of the Senate, the inspector general’s office said the CBP leadership had “virtually no warning” the executive order was coming and “was caught by surprise.”

And it says DHS and CBP leaders didn’t know the answers to basic questions, such as whether the order would apply to green card holders. CBP’s inability to issue “definitive guidance in the early days” of the order’s implementation, the office found, “contributed to significant delays” at ports of entry.

The report also found problems in the government’s compliance with court orders lifting the ban, including wrongly preventing passengers from boarding planes to the U.S.

The findings are referenced in letters to members of the Senate complaining that DHS is stalling the release of a comprehensive report the inspector general’s office compiled looking into problems with the order’s implementation.

Trump’s original travel ban sought to temporarily suspend the U.S. refugee program and block the entry of nationals from seven majority-Muslim countries into the U.S. The order sparked chaos at airports and a flurry of lawsuits, which led to the order’s suspension. The administration has since made several attempts to revise the order to try to better hold up to legal scrutiny.

The letters summarized the findings broadly, but Inspector General John Roth said he was barred from releasing the rest of the report, which was submitted to DHS on Oct. 6, until the department signs off on what it considers privileged information.

DHS spokesman Tyler Houlton defended the department, saying its “many officials conducted themselves professionally, and in a legal manner, as they implemented an Executive Order issued by the President.”

But he said that material within the report “is covered by privileges afforded by well-recognized law.”

“This should come as no surprise as many of the activities in implementing the Executive Order were conducted amidst a large number of lawsuits and, later, court orders that shaped the Department’s response,” he said in a statement.

Sens. Dick Durbin and Tammy Duckworth, both Illinois Democrats, said in a statement Tuesday, “We know that CBP officers have a difficult job — but when the President failed to provide even the most basic guidance or warning regarding his discriminatory and unconstitutional Muslim Ban, he clearly didn’t make it any easier.”

The senators said they were disappointed that DHS has yet to release the full report. “The rule of law and our Constitutional protections mean little if law enforcement is empowered by the President to disregard them,” they wrote. “If the Trump Administration decides to bury an Inspector General report suggesting that’s what happened, there will be repercussions in Congress.”

Roth, who became inspector general in 2014, said in the letters that he was “particularly troubled by the Department’s threat to invoke the deliberative process privilege, as this is the first time in my tenure as Inspector General that the Department has indicated that they may assert this privilege in connection with one of our reports or considered preventing the release of a report on that basis.”

“In fact, we regularly have published dozens of reports that delve into the Department’s rationale for specific policies and decisions, and comment on the basis and process on which those decisions were made. Indeed, that is at the heart of what Inspectors General do,” he added.