North Korean banks subject to international sanctions have recently been banned by Swift from using its global financial messaging service, according to a statement from the Belgium-based Society for Worldwide Interbank Financial Telecommunication.

Swift said it had recently been informed by Belgian authorities that they would no longer provide the “necessary authorizations” for it to continue offering services to North Korean banks covered by United Nations sanctions. “As a result, Swift suspended access of UN-designated North Korean entities to the Swift financial messaging service,” the statement said.

North Korea has further stoked regional tension by firing four ballistic missiles into the sea near Japan Monday. In response, the U.S. reaffirmed its military alliance with Japan and has announced the start of the deployment of its Thaad missile-defense system in South Korea.