Isaac Benbenisti, who is to become CEO of Israeli spy company NSO Group, has resigned after the company was blacklisted by the U.S. Commerce Department.

Benbenisti, who joined NSO in August, was recently appointed to succeed outgoing CEO Shalev Hulio, who co-founded the company and was expected to take on new roles as vice chairman and global president. In light of recent developments, Hulio will remain CEO as Benbenisti leaves the company.

In excerpts from Benbenisti’s resignation letter to NSO’s chairman Asher Levy, Benbenisti stated that “in light of the special circumstances that have arisen” following the U.S. decision, and not being able to carry out his vision for NSO, he “would not be able to assume the position of CEO with the company”.

Last week, the U.S. Commerce Department put NSO, accusing it of selling spying software to foreign governments that used the device to target government officials, journalists and other high-profile figures.

The company’s blacklist means that exports to NSO from partners in the U.S. are restricted, making it very difficult for U.S. security researchers to provide them with information about computer vulnerabilities.

An NSO source said the company is currently challenging the U.S. decision and is in contact with European customers.

NSO expressed deep dismay at the U.S. blacklist decision, reiterating that it had terminated contracts with government agencies that abused products it promotes as genuine tools for fighting crime and terrorism.