United Airlines has joined the growing list of airlines that are reducing service to Venezuela in protest over the government’s delay in paying multiple carriers for tickets purchased in the country.

United said it will reduce its service by 43 percent, trimming its daily flight from Houston to Caracas to just four times a week beginning Sept. 17.

This comes on the heels of Delta’s announcement last week that it would cut daily service from Atlanta to Caracas down to just one weekly flight starting Aug. 1. American previously announced it would cut its scheduled service to Venezuela by a whopping 79 percent. Effective July 1, American now flies just 10 scheduled weekly trips to the country.

At issue is the way the country takes in money for airline tickets and then distributes it. Venezuela insists all money collected in ticket sales must be in bolivars, which it then deposits into a government-controlled account. The government then disperses the money.

But there has been no repatriation of the money. The government is running out of cash and has not made any payments.

Venezuela owes 24 airlines across the world $3.8 billion in ticket sales, according to the International Air Transport Association (IATA), the trade association that represents virtually every airline.

More than a dozen airlines, including Air Canada and Alitalia, have either trimmed service to Venezuela or eliminated it altogether.