"We clearly see the coordination of this acts by the Russian special services," Nalyvaichenko said.
According to him, the recent events in Kharkiv suggest that the threat remains.
"Either the SBU or the Interior Ministry will be working strenuously there," he added.
Nalyvaichenko stressed that the most important in dealing with similar threats is to unite efforts of the Interior Ministry, the Security Service, and the community.
As reported, 11 people were hospitalized as a result of the explosion in the rock pub "The Wall" on 13 Rymarska Street in Kharkiv downtown Nov. 9.
The explosion of a freight train car occurred in the Kharkiv region Nov. 9 without casualties.
The explosion sounded near the electrical substation of the Kharkiv Military Medical Clinical Center of the Northern Region on 14 Trinkler Street of Nov. 20 evening.
There was an explosion near the "Osnova" terminal yard of the Kharkiv railway hub of the Izium and Kupiansk directions in Kharkiv at approximately 10:30 p.m. Nov. 21.
The explosion took place near the fence of the military base near the 5-storey residential building on 55A Poltavskii Shliakh Street, in Kharkiv at about 11:50 p.m. Nov.24.