Denmark on the Digital Frontline: Lessons learned from Ukraine

Drawing on data from Ukraine, researchers from the IT University of Copenhagen are investigating how to prepare Danish society for cyberattacks on the digital critical infrastructure.

Written 3 November, 2025 16:27 by Jari Kickbusch

Denmark is under attack from foreign state actors. According to recent threat assessments conducted by Danish Centre for Cyber Security (CFCS), the cyber threat landscape facing the digital critical infrastructure has intensified significantly. In March 2025, for example, the CFCS raised the cyber activism threat level for the telecommunication sector to "high", particularly due to geopolitical tensions such as Russia’s invasion of Ukraine and the Danish government's support to Ukraine.

The intensified cyber threat landscape is investigated by Oksana Kulyk, associate professor at the IT University of Copenhagen, who leads a group of researchers who are looking into how to prepare Danish society for cyberattacks on the telecommunication sector. The project, which is funded by the National Defence Technology Centre (NFC), sheds light on the vulnerabilities of Danish critical infrastructure and offers a sobering look at how cyberwarfare is reshaping national security.

"A highly digitalised country such as Denmark heavily relies on functioning digital services. Daily services such as online banking or buying train tickets, and critical services such as healthcare, which depend on digital systems, all rely on the underlying digital infrastructure. Telecommunication outages that result in digital infrastructure disruptions can therefore cause these services to become unavailable. Depending on the scope of the outage, people might furthermore be unable to get support or accurate information from the government, connect to emergency services in case they need help, or get in touch with their family to check on their well-being. Unless Danish society can prepare for such outages, the consequences can be drastic,” says Oksana Kulyk.

Vulnerability

The Danish society’s dependency on telecommunications infrastructure to support critical societal functions, economic activity, and national security is recognised by the Ministry for Society Security and Emergency Preparedness and The Danish Resilience Agency (SAMSIK), which in the folder “Be Prepared for Crises” encourages households to be self-sufficient for three days during a crisis. In the folder, SAMSIK emphasises that telecommunication is a key part of individual and household preparedness, while – at the same time – recognising that in a crisis, access to digital communication may be disrupted. The recognition of both the importance and vulnerability of telecommunication leaves us with an open question: How prepared is the Danish society, businesses, and citizens for telecommunication outages?

To study how people, companies, and government institutions in a digitised society act during telecom outages, Oksana Kulyk and her colleagues went to Ukraine where citizens and companies have experienced a large number of cyber and kinetic warfare attacks, which have left them without mobile and internet connection.

“Ukraine has extensive experience with Russian cyberattacks on critical infrastructure. The attacks started as a prelude to the invasion of Crimea in 2014 and intensified after the full-scale invasion in 2022. Ukrainian society has now, out of necessity, learned to understand the importance of cybersecurity protection for critical infrastructure. In particular, telecommunication outages have been experienced by many people and organisations, and different mitigation measures have been employed, including strengthening the organisation’s cybersecurity posture, setting up alternative communication channels such as Starlink or portable radio stations, becoming ready to switch to paper-based communication, or getting a SIM card from an alternative telecommunication service provider in case the primary provider stops working. These and other methods, which have been applied and tested in Ukraine, can be studied to understand how Danish society can be prepared in the most effective way,” she says. 

What to do about it

Oksana Kulyk explains that the report, which is expected to be published primo 2026, will suggest some steps to take for the Danish government, companies, and researchers in order to strengthen the cyber defence and preparedness. Further, the report will include recommendations for directions for future research.

“Attacks on critical infrastructure can have impacts that reach far beyond the target organization. Protection against and mitigation of these attacks requires a systematic approach, involving public and private sector stakeholders as well as international collaborations. Such an approach requires consideration of many factors, addressing both technical challenges as well as human and societal aspects of cyber resilience,” ends Oksana Kulyk.