JERUSALEM (JTA) — A strike by Israeli Foreign Ministry employees is threatening high school educational trips to Poland.

Up to 20 groups of Israeli high school students are scheduled to travel to Poland as part of their studies of the Holocaust in August. The up to 2,000 students have already paid more than $1,400 each for their trips, which are non-refundable, according to Israeli news reports.

At issue is the refusal under the current ministry employees’ labor sanctions to issue diplomatic passports for the security guards. The groups may not leave for Poland without Israeli security guards.

On Monday, the Jerusalem Labor Court refused to order the employees to issue the diplomatic passports to the security guards to ensure that the trips take place. Education Ministry officials met with the tour operators on Tuesday to discuss options, which include cancelling the trips, according to Haaretz.

The high schools have threatened to sue the workers’ union for damages if the trips are cancelled.

The work stoppage is part of a 4-month-old labor dispute. The ministry workers are protesting salary cuts and poor compensation packages offered to spouses of overseas diplomats.

The strike has affected foreign travel by Israeli officials, official visits to Israel by foreign delegations, and the ability of new Israeli ambassador to the United States Ron Dermer to take up his position.