Ukraine’s security service said Monday it had detained a Russian informant who planned to assassinate Ukrainian President Volodymyr Zelenskyy last month.

The alleged informant “was preparing a Russian airstrike in the Mykolaiv region during the visit of the president of Ukraine,” the Ukrainian Security Service (SBU) said.

The woman was “gathering intelligence” about the “the time and list of locations of the approximate route” of Zelenskyy’s visit to Mykolaiv at the end of July. Based on the information, a “massive” Russian airstrike would have assassinated Zelenskyy, the SBU said.

The plotter was caught “red-handed,” according to the SBU, while giving information to the Russians. The SBU subsequently increased security measures after the informant’s “subversive activities” were uncovered.

The informant, who has not been named, had previously worked as a saleswoman in a military store and lived in the southern Ukrainian city of Ochakov.