Censor.NET reports citing the statement by the president's press office on Twitter.
"I have instructed to bring all units at border with Crimea and demarcation line in the Donbas on high alert," Poroshenko said.
On Aug. 10, the FSB released an official statement about averted terrorist attacks in annexed Crimea "prepared by the Main Intelligence Directorate of Ukraine's MoD in order to target critical life-supporting and infrastructure facilities inside the peninsula."
The Ukrainian MoD refuted the FSB's allegations on the involvement of Ukraine's intelligence in subversive activities in Crimea and called them an attempt of the Russian Federation to justify its aggression in the territory of the annexed peninsula.
The Main Intelligence Directorate of Ukraine's MoD denies the information about an alleged breakthrough of Ukrainian "subversive and terrorist groups" in the territory of Crimea. According to Defense Intelligence representative Vadym Skibitskyi, such allegations by the FSB is one of the elements of incitement and destabilization of the situation in Ukraine: "provocation is an element of the hybrid war which the Russian Federation is waging against us."
President Petro Poroshenko said the Russian allegations were groundless and served as "a pretext for more military threats against Ukraine."