President Donald Trump’s hold on security assistance to Ukraine was illegal, according to the federal government’s independent watchdog.

The new determination by the Government Accountability Office, or GAO, comes as the Senate is set to take up the articles of impeachment against Trump, which were delivered from the House on Wednesday.

Last June, Trump placed a hold on $214 million of security assistance from the Pentagon for Ukraine, as it battles Russian-led separatists in its eastern provinces. The White House Office of Management and Budget, or OMB, told Congress, which had passed the budget law appropriating those funds, that they were being withheld to ensure they weren’t spent “in a manner that could conflict with the Presidents foreign policy.”

But GAO said that the executive branch can’t use that kind of policy reason to withhold funds appropriated by Congress.

“OMB violated the [law] when it withheld” the Ukraine assistance “for policy reasons,” the report concludes.

Trump has always maintained he’s done nothing illegal.

The GAO is an independent, nonpartisan watchdog agency that investigates the federal government on behalf of Congress, taking up requests on behalf of both Republicans and Democrats.

Trump had placed a hold on a total of $391 million of security assistance to Ukraine and has provided various reasons for doing so — including that European allies have not contributed enough to Ukraine’s security or that he was concerned the money would be well-spent and not used for corruption.

The other pot of money came from the State Department, and the GAO is still investigating whether its funds were withheld for legitimate reasons, but said that the department and OMB have failed to comply with their investigation.

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