The peak summer travel season in the US is months away, but the lines at airport security already are getting unbearable.

The Chicago Tribune reports that 1,000 American Airlines passengers missed flights at O’Hare International Airport in March because of long security lines:

Since it started monitoring TSA wait times in late February, American Airlines has seen typical waits of 30 minutes to 60 minutes — with a high of 90 minutes. Mornings tend to be worst, but long waits are seen throughout the day.

“TSA is our No. 1 problem right now, and it’s only going to get worse,” an American Airlines spokeswoman told the Tribune.

United Airlines has concerns, too. Spokesman Charles Hobart tells Quartz that the carrier has been working with the TSA to address “longer than normal wait times at some security checkpoints.”

The TSA has reduced its screening staff in recent years, from 47,630 workers in 2011 to an estimated 41,928 in 2016, according to US Department of Homeland Security budget documents. Meanwhile, an alternative screening option offered to passengers, known as TSA Precheck, has not been as popular as planned. The program costs $85 to enroll and gives approved passengers an expedited screening process.

The TSA, for its part, says “the number one problem” right now for any airline is the threat of global terrorism. The agency says it has a “robust plan” to deal with the increasing level of travel “including more canine use, encouraging pre-check enrollment, overtime, accelerated hiring and more.”

If it’s only April and the airlines already are worried about the lines at security, it’s a bad omen for what’s to come. As I pointed out in November, US airports are at their busiest during the summer months, which means the busiest travel days of 2016 are still ahead of us.