As US airports are in chaos, Trump threatens traffic controllers with severe penalties: 'Report to work immediately!'

US President Donald Trump asked air traffic controllers to return to work on Monday, as government-imposed flight cuts and air traffic staff absences continue to wreak havoc on the US aviation sector, Reuters reports.

Trump added that he would reward those who did not take time off during the 41-day “shutdown” of the federal government (“shutdown”), but it is unclear how many controllers could benefit from the White House leader's promise. Trump has indicated, instead, that he will accept the resignation of those who have taken leave.

“All air traffic controllers must return to work, NOW!!! Those who do not will be severely penalized,” Trump wrote in a post on his social network, Truth Social. “REPORT TO WORK IMMEDIATELY,” the US president added, using his signature all-caps to get his message across.

Shares of major US airlines, including American Airlines, Delta Airlines and United Airlines, fell after Trump's online post.

The government “shutdown” has led to a shortage of air traffic controllers who, like other federal employees, have not been paid for weeks. Officials said it was unclear under the controllers' union contract how they might be penalized or the source of Trump's proposed $10,000 bonus.

Last week, the head of the Federal Aviation Administration (FAA), Bryan Bedford, said that 20-40 percent of controllers had not reported for work on any of the days since the “shutdown” began at the 30 largest US airports.

Staffing problems worsened over the weekend and Saturday was the worst day for employee attendance since the government “shutdown” began, Transport Secretary Sean Duffy said on Sunday.

Asked about Trump's claims, National Air Traffic Controllers Association President Nick Daniels said Monday that the union would appreciate any recognition of the work of controllers and that “we will work with the administration on any issues that come up. Air traffic controllers will continue to report to work during this shutdown.”

Airlines canceled 1,700 flights in the US on Monday, and the numbers are expected to rise this week after the FAA imposed a 10% reduction in flights starting last Friday.

FlightAware, a flight-tracking website, said 3,480 flights had been delayed as of 11:30 a.m. ET (16:30 GMT) on Monday, after 2,950 flights were canceled and nearly 11,200 were delayed on Sunday, the worst day of flight disruptions since the government shutdown began on Oct. 1.

This month's Chicago winter storm is also disrupting air traffic.

The government “shutdown,” the longest in US history, has forced 13,000 air traffic controllers and 50,000 Transportation Security Administration agents to work without pay.

The FAA is about 3,500 air traffic controllers short of the targeted staffing level. Many of them were working mandatory overtime or six days a week even before the government shutdown. Duffy has offered incentives to keep more retirement-eligible controllers in the system as he works to speed up hiring and launches a $12.5 billion initiative to overhaul air traffic control.

Late Sunday, the FAA announced it was suspending general air traffic at 12 airports experiencing air traffic control staffing issues, including Chicago O'Hare and Reagan Washington National.

The US Senate voted late Sunday in favor of a bill to end the government shutdown.

The FAA has instructed airlines to reduce daily flights by 4 percent starting last week at 40 major airports for air traffic control safety reasons. The reduction in the number of flights must reach 6% on Tuesday and then 10% by November 14. An important question for airlines is when the FAA will lift government-imposed flight restrictions. Duffy said he first wants to see improvements in air traffic control personnel and safety data.