The Israeli government is blocking medical workers from entering or leaving Gaza, twice canceling the departure of seven U.S.-based physicians on a medical mission there, according to a group of doctors in Gaza who spoke to The Intercept.

The temporary suspension of travel is the latest in a crushing set of restrictions that Israel has used to sever Gaza’s contact with the outside world, compounding food, fuel, and medical care shortages for a population subjected to more than two years of genocide. Large backlogs of patients in Gaza need specialized treatments and surgeries, so volunteer medical specialists come with much-needed supplies to relieve some of the demand.

“When you do something like this, it throws all of that to the wayside and we struggle with our ability to treat those patients,” said Dr. Thaer Ahmad, a Chicago-based physician who has previously volunteered in Gaza. “This continues to have really profound implications on Gaza’s most vulnerable people.”