Ukrainian police arrested a 31-year-old man on Friday accused of killing a woman and her daughter, and who they also suspect was planning to mow down citizens with a truck, like the attacks on the Berlin Christmas market and in Nice.
Police said the man had murdered two people in a village in the southern Odessa region before setting fire to two houses and then escaping in a stolen truck and hiding in an abandoned home before officers caught him.
Based on information they had received from a friend of the man, police said he was planning to run over a large crowd of people with the truck.
The attack in the German capital days before Christmas killed a dozen people and injured 56, while a similar incident in Nice, France, on Bastille Day killed 86 people and injured more than 400.
European capitals have tightened security ahead of New Year's celebrations, erecting concrete barriers in city centres and stepping up police numbers after the attack in Berlin. New York City will also take steps to protect revellers.
Alyona Voitenko, a spokeswoman for the Odessa police, said: "We knew that he was armed and dangerous."
She said the man had threatened an attack by saying: "Odessa will cry, I will ram into the city in a truck."