Russian hackers breached the system of Ukrainian telecoms operator Kyivstar in a cyberattack that caused significant destruction and served as a warning to the West, according to Ukraine’s cyber spy chief. The attack, suspected to be the work of Sandworm, a Russian military intelligence cyberwarfare unit, demonstrated the vulnerability of telecoms operators to cyber threats. The hackers infiltrated Kyivstar’s system in May 2023 and had full access since November of that year.