The White House budget office asserts in a new legal memo that it withheld military aid to Ukraine as a temporary move to study whether the spending complied with U.S. policy — and not as a political effort to block Congress’s spending decisions.

The office first began discussing the aid on June 19, the day President Trump learned of the aid from an article in the Washington Examiner and questioned the wisdom of the spending. That move sent aides scrambling, according to a senior administration official who spoke on the condition of anonymity to share internal conversations.

The Office of Management and Budget extended the temporary hold on the aid eight times in August and September, the last time being Sept. 10. Almost immediately after that hold, the money was released, according to the new memo, which was reviewed by The Washington Post.

The memo details the White House’s latest legal rationale for freezing foreign aid to Ukraine over the summer. OMB general counsel Mark Paoletta wrote the memo to respond to a request from the U.S. Government Accountability Office, which had asked why the aid had been delayed.

Those delays are now at the center of House Democrats’ accelerating impeachment probe of Trump. House Democrats unveiled on Tuesday two articles of impeachment against the president, saying he abused the office of the presidency and obstructed a congressional investigation into his actions regarding the aid to Ukraine.

OMB has been ensnared by the controversy for months. Two career OMB officials resigned in part over concerns about the agency’s hold on the Ukrainian assistance, according to the testimony of Mark Sandy, a career OMB official. Current and former OMB employees have described the hold as highly unusual.

OMB has denied that the resignations came over the aid.

Government officials have testified that they were alarmed that the aid to Ukraine was withheld, as OMB staffers pushed to get the aid out as soon as possible, according to Sandy. Some have told Congress they worried Trump was trying to use government funds for personal political gain.

Trump agreed to release the aid under pressure to do so from Vice President Pence and Sen. Rob Portman (R-Ohio) in a phone call on Sept. 11.

In the memo, Paoletta says that the agency frequently puts temporary holds on money already signed into law and that Congress also stops money that has already been approved from reaching federal agencies.

In a footnote to the memo, OMB calls on the nonpartisan GAO to look into what it says are Congress’s own moves to hold up money already signed into law.

Paoletta asserts that while OMB must notify Congress before delaying allocation of some funds, the Ukraine assistance amounts to a “programmatic delay” that does not require notification, citing a prior GAO opinion.

Paoletta authorized the repeated delays in the spending while awaiting a decision from Trump on the matter, according to the administration official.

“For decades, OMB has routinely used its apportionment authority to prevent funds from being used,” Paoletta wrote.

“Often, in managing appropriations, OMB must briefly pause an agency’s legal ability to spend those funds for a number of reasons, including to ensure that the funds are being spent efficiently, that they are being spent in accordance with statutory directives, or to assess how or whether funds should be used for a particular activity.”

OMB has previously given partial explanations of its conduct over aid related to Ukraine, but the memo represents its most fully articulated defense to date of the legality of the hold it placed on the assistance.

Importantly, the agency’s memo does not attempt to rebut Democrats’ contention that Trump abused his power by seeking to pressure a foreign nation to open an investigation into a political rival or that he obstructed justice in deterring the investigation into his conduct.

Several OMB divisions wrote a joint memo in August recommending the military aid go to Ukraine as soon as possible, according to Sandy’s testimony, noting the assistance “is consistent with the national security strategy . . . in terms of supporting a stable, peaceful Europe.”

Paoletta’s new memo states that the Ukrainian assistance was put on hold in response to an administration directive “pending a policy decision,” with internal discussions on the aid beginning June 19.

That was the same day the president read an article in the Washington Examiner about the Pentagon’s plans to send $250 million in weapons to Ukraine, according to the administration official who spoke on the condition of anonymity. The president’s questions set off a scramble to answer his questions about the aid, this person said.

The memo says that “at no point during the pause” did Defense Department attorneys tell OMB the Ukrainian funding would be prevented from being spent before the end of the year.

OMB’s memo also stresses that the Defense Department indicated to its staff that it didn’t intend to release most of the security funds to Ukraine until September, so the damage of withholding the funds was minuscule.

Some experts have questioned OMB’s argument that it was following the president’s direction, given the evidence that Trump had political motivations for withholding the money.

“It’s probably true that it’s within the power of the executive branch, and OMB, to put constraints on funds to make sure they are going out appropriately. We have seen in the past that money has been held out or put aside,” said Mark Mazur, a former Treasury Department assistant secretary for tax policy in the Obama administration. “But it’s a little weird to have an ‘I’m only following orders’ defense here.”

OMB officials also compiled a 10-page list of government records that, they say, show Congress held up various programs that had already been signed into law.

The examples include Ukraine funding allocated through the Assistance for Europe, Eurasia, and Central Asia program, which OMB’s documents say was held up in 2017, as well as tens of millions of dollars for programs in countries such as Libya, the Philippines, Mexico and Sri Lanka.

Carol D. Leonnig contributed to this report.