Qatar Airways Group has launched legal action against the four neighboring states that have halted airline movements between them and Qatar for more than three years.

Bahrain, Egypt, Saudi Arabia and the UAE barred air services between themselves and Qatar in June 2017, alleging Qatari state support for several bodies they regarded as terrorist organizations. Qatar rejects the accusation.

Their move has blocked neighboring airspace to Qatar Airways flights, requiring the company’s aircraft to take an extended flightpath over Iranian territory, adding around 25 minutes’ flying time to sectors and significantly increasing the company’s costs.

The dispute is scheduled for a hearing at ICAO at an as-yet-unspecified point in the coming months.

In the latest move, Qatar Airways Group has launched four international investment arbitrations against the neighboring states. These seek redress for the states’ actions to remove Qatar Airways from their markets and to forbid the airline from flying over their airspace. The airline is seeking “at least $5 billion” in compensation for what the company describes as their unlawful actions.

“For three decades, Qatar Airways made substantial investments in the four blockading countries in order to serve hundreds of thousands of passengers and to transport tens of thousands of tons of cargo to and from each of these countries annually,” the company said in a July 22 statement.

The countries’ actions against Qatar “specifically targeted Qatar Airways, with the objective of shuttering Qatar Airways’ local operations, destroying the value of the airline’s investments and causing widespread damage to Qatar Airways’ global network of operations,” the company alleged.

Qatar Airways said it is seeking full compensation for the alleged damages in four investment arbitrations, brought under three separate treaties: the OIC Investment Agreement, the Arab Investment Agreement, and the bilateral investment treaty between the State of Qatar and Egypt.

“The Notices of Arbitration make clear that by imposing the measures against Qatar Airways, the blockading states have violated their obligations under the agreements, including by expropriating and failing to adequately protect and secure Qatar Airways’ investments, discriminating against Qatar Airways, and failing to provide fair and equitable treatment to the airline and its investments,” the company said.

“The decision by the blockading states to prevent Qatar Airways from operating in their countries and flying over their airspace is a clear breach of civil aviation conventions and several binding agreements they are signatories to,” Qatar Airways Group CEO Akbar Al Baker said. “After more than three years of efforts to resolve the crisis amicably through dialogue yielded no results, we have taken the decision to issue Notices of Arbitration and pursue all legal remedies to protect our rights and secure full compensation for the violations.”