President Donald Trump notified House Speaker Nancy Pelosi Thursday that she would not be allowed to use military aircraft for an upcoming trip to Afghanistan, citing the budget shutdown.

“I’m sorry to inform you that your trip to Brussels, Egypt and Afghanistan has been postponed,” Trump wrote in a signed letter released by the White House. “We will reschedule this excursion when the Shutdown is over.”

The letter seemed to be in direct response to Pelosi asking the president to postpone his State of the Union address, held in the House chambers of Congress, until the shutdown is over. In her notice, Pelosi said that the unpaid Secret Service and Department of Homeland Security may not be able to provide adequate security.

Pelosi’s travel had been tasked out by the Office of the Secretary of Defense and approved, the Air Force said. That travel would have mostly likely been supported by the 89th Airlift Wing and other units overseas who regularly provide transport to dignitaries, such as generals and Cabinet members. The dignitaries typically fly on C-32 or C-40 planes, which are specially outfitted 757 and 737 official government aircraft with blue and white livery.

The CODEL to Afghanistan included a required stop in Brussels for pilot rest. In Brussels, the delegation was scheduled to meet with top NATO commanders, U.S. military leaders and key allies–to affirm the United States’ ironclad commitment to the NATO alliance. (1/4) — Drew Hammill (@Drew_Hammill) January 17, 2019

The direction to cancel the tasking was sent to the Air Force by the Office of the Secretary of Defense.

“The tasking has been turned off,” a defense official said.

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DoD is one of the few agencies that was fully funded for 2019 and its forces, aircraft and ships are not impacted by the shutdown. The Coast Guard, which is funded under the Department of Homeland Security, has not been funded.

A defense official said it was not a resourcing issue, i.e., there were available aircraft.

House Speaker Nancy Pelosi speaks during a news conference on Capitol Hill in Washington, Thursday, Jan. 17, 2019. (Carolyn Kaster/AP)

Several House members were scheduled to travel with Pelosi on the trip, one of numerous congressional delegations conducted by lawmakers in connection with their other congressional duties.

Overseas trips with lawmakers are almost always handled through military aircraft. Trump in his letter told Pelosi that “if you would like to make your journey by flying commercial, that would certainly be your prerogative.”

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In March 2018, Pelosi lead a similar congressional delegation to Jordan, Israel and Afghanistan with 11 other House lawmakers. Former House Speaker Paul Ryan and then-House Armed Services Committee Chairman Mac Thornberry arranged a similar trip to visit troops in Afghanistan in October.

The president’s move drew immediate rebuke from Sen. Lindsey Graham, R-S.C., who said lawmakers should not be blocked from visiting troops serving in combat zones overseas.

“One sophomoric response does not deserve another,” he said in a statement. “Speaker Pelosi’s threat to cancel the State of the Union is very irresponsible and blatantly political. President Trump denying Speaker Pelosi military travel to visit our troops in Afghanistan, our allies in Egypt and NATO is also inappropriate.”

A military bus carrying members of Congress headed overseas as part of an official trip to Afghanistan circles Capitol Hill after President Donald Trump abruptly cancelled the visit Thursday, Jan. 17, 2019, amid ongoing political fights over the continued government shutdown. (Leo Shane III/Staff)

The shutdown reached day 27 on Thursday, as congressional Democrats and Trump continue to spar over about $5 billion in funding for his controversial southern border wall project.

More than 400,000 federal workers have been required to work without pay for the last month, including most service members in the Coast Guard. Another 300,000-plus have been furloughed without pay while the budget dispute continues.

The partial shutdown has not directly affected the Department of Defense, whose budget was approved last fall.