Nancy Pelosi was supposed to be in Brussels on a stopover on Friday to meet Nato officials before travelling to Afghanistan to meet US troops. An hour before her departure, she received a "no-go".
The letter from President Trump to the Democrat House speaker, sent a few hours before her scheduled departure said, "I am sorry to inform you that your trip to Brussels, Egypt, and Afghanistan has been postponed. We will reschedule this seven-day excursion when the shutdown is over," describing Pelosi's official but low-profile visit as "public relations".
Pelosi's office also commented that Egypt had never been on the itinerary.
Trump added that Pelosi might like to take a regular flight instead of a US Air Force plane for her fact-finding mission.
State of disunion
The president's move followed Pelosi's suggestion that he postpone the annual State of the Union address to Congress, or else do it from the White House.
At the same time, Trump cancelled US representation at the Davos economic forum in Switzerland. He had previously said he would not attend.
The US government shutdown is due to Trump's refusal to approve funding for a host of departments. His move came in retaliation for the Democratic-led House's refusal to approve his US-Mexico border wall project.
The shutdown is in its fourth week. Hundreds of thousands of government employees have not been paid their salaries or have been obliged to stay at home.
Diplomatic quest for peace in Afghanistan
The row comes as US and other diplomatic efforts intensify to try to end the 17-year-long conflict in Afghanistan.
The US envoy to Afghanistan, and Washington's former ambassador to the country, Zalmay Khalilzad is currently in Pakistan for talks. He has recently visited China, the United Arab Emirates and India.
Khalilzad, said in Kabul this week that he hopes for fresh talks with the Taliban very soon. He met Taliban representatives at the end of 2018 in Doha and Abu Dhabi. China has also invited the Taliban for talks.
Russia and Iran have also held meetings with the militants in recent months. Saudi Arabia, the UAE and Pakistan are pitching in alongside the US peace efforts.
Elections are slated for the second half of this year in Afghanistan, although the security risks are still high.
Several hundred protesters marched yesterday in three cities in southern and eastern Afghanistan, Kandahar, Khost and Jalalabad, calling for a cease-fire and an end to the war.
A peace movement launched in May 2018 by a few civilians who travelled 700 kilometres from Lashkar Gah, in the southern province of Helmand, to the capital Kabul. By the time they reached their destination in June, hundreds of other marchers had joined them.