House Speaker Nancy Pelosi (D-Calif.) on Friday officially canceled a congressional delegation trip to Afghanistan after President Donald Trump leaked her travel plans to retaliate against her request to postpone his State of the Union address until after the government shutdown.

“After President Trump revoked the use of military aircraft to travel to Afghanistan, the delegation was prepared to fly commercially to proceed with this vital trip to meet with our commanders and troops on the front lines,” Pelosi’s spokesman Drew Hammill said in a statement. The statement continued:

“In the middle of the night, the State Department’s Diplomatic Security Service provided an updated threat assessment detailing that the President announcing this sensitive travel had significantly increased danger to the delegation and to the troops, security, and other officials supporting the trip. This morning, we learned that the Administration had leaked the commercial travel plans as well. In light of the grave threats caused by the President’s action, the delegation has decided to postpone the trip so as not to further endanger our troops and security personnel, or the other travelers on the flights.”

Hammill said later in an email that Pelosi canceled the trip after her office found out that multiple administration officials had attempted to leak the congressional delegation’s commercial flight plans through reporters.

The White House did not immediately return a request for comment on Pelosi’s statement.

Later on Friday, the White House announced that under the government shutdown, no congressional lawmakers will be allowed to use “any government owned, rented, leased, or chartered aircraft,” or any executive branch funds for travel without White House approval.

A senior White House official, who would not comment on the record, hotly denied Pelosi’s assertion that Trump’s administration leaked the delegation’s travel plans.

“When the speaker of the House and about 20 others from Capitol Hill decide to book their own commercial flights to Afghanistan, the world is going to find out,” the official said. “The idea we would leak anything that would put the safety and security of any American at risk is a flat-out lie.”

On Thursday, Trump sent a letter to Pelosi canceling the planned congressional delegation trip aboard a government plane to visit troops in Afghanistan, and suggested she and the congressional delegation take commercial flights instead. Trips like these are typically kept top-secret due to security concerns, so Trump’s tit-for-tat letter canceling the trip had the effect of revealing the trip’s details.

Trump’s petty letter to Pelosi on Thursday added more drama to the showdown over the government shutdown, which reached its 28th day on Friday and continued to create uncertainty for hundreds of thousands of government workers who are furloughed or working without pay. Trump is demanding $5 billion for his promised border wall, which Democrats have called immoral and a waste of money.

On Wednesday, Pelosi requested that Trump postpone the Jan. 29 State of the Union address until the government reopens, citing the strain that the high-profile, high-security event would place on furloughed workers in the Secret Service and Department of Homeland Security. Instead of answering the request, Trump hit back at Pelosi with the travel cancelation.

This article has been updated to include an unnamed White House official denying that Trump’s administration leaked congressional travel plans.