MOSCOW (Reuters) - Russia said on Thursday it was preparing to ban the Atlantic Council, a think-tank formerly run by the U.S. ambassador to Moscow, which Russia’s prosecutor general described as a security threat.

“It has been established that the activities of this organization present a threat to the fundamentals of the constitutional order and security of the Russian Federation,” the prosecutor general’s office said.

It gave no further details of the reasons for the ban.

The move follows steps taken by Moscow against several other foreign non-government organizations since Russia’s relations with the West deteriorated over the Ukrainian crisis in 2014 and financial sanctions that followed.

The General Prosecutor’s Office said it had handed over its ruling to the Russian ministry of justice.

“We are proud of the council’s long tradition of work with Russians and on Russia, and are disappointed that Russian authorities have announced this step,” the Atlantic Council said in a statement sent by email to Reuters, adding that it had not been informed of the decision by the authorities.

U.S. ambassador Jon Huntsman served as chairman of the think tank from 2014 until 2017, when he was appointed to his diplomatic post by President Donald Trump.