The National Intelligence Service is conducting a review of cyber terrorism preparedness on the country’s energy infrastructures including electricity, gas and water supply networks, the agency announced Monday.

The measure comes after the recent cyber attacks in the United States that targeted the data of the energy infrastructures and demanded payment in cryptocurrency.

The NIS has already looked into the nation’s control system of water purification plants with the Ministry of Environment and the Ministry of the Interior and Safety. The agency paid close attention to the network’s security updates.

The joint examination between the NIS and the Ministry of Trade, Industry and Energy checked the country’s major gas production and control system, managed by the Korea Gas Corp. Issues regarding unauthorized access, the latest update in security system, and a recovery plan against ransomware cyber attacks were examined.

The agency plans to check the Korea Power Exchange’s information and communication system with Korea Electric Power Corporation next month.

“With the revised NIS Act, we carry out measures to collect, analyze and respond to information regarding to cyber security, including the hackers,” an official at National Intelligence Service said. “If weaknesses are spotted through examination, we plan to take measures by analyzing the results and applying the social infrastructure needed to protect national and public institutions from cyber attacks.”