The U.S. Embassy in Montenegro has warned Americans that an ongoing ransomware attack in the country could cause widespread disruption to key public services and government services.

The ransomware attack, first confirmed by Montenegro’s Agency for National Security (ANB) last week, targeted government systems and other critical infrastructure and utilities, including electricity, water systems and transportation. At the time of writing, the official website of the government of Montenegro is unavailable and reports suggest that several power plants have switched to manual operations as a result of the attack.

Officials in Montenegro claimed no data was stolen and claimed that no permanent damage was done as a result of the attack.

However, Montenegro’s ANB declared that the country was “under a hybrid war,” and blamed “coordinated Russian services” for the attack. Relations between the two countries have remained strained since Montenegro joined the NATO alliance of Western countries in 2017, after which Russia threatened retaliatory action.

The U.S. Embassy in Montenegro has since published its own notice, writing that the government was facing a “persistent and ongoing” cyberattack. “The attack may include disruptions to the public utility, transportation (including border crossings and airport), and telecommunication sectors,” the Embassy warned. It advised citizens residing in the Balkan state to limit travel, review personal security plans, and “be aware of your surroundings.”