A Russian spy at the center of a secret operation to smuggle high-tech weapon components into Russia has left Japan after his activities were disclosed by The New York Times, a senior Ukrainian intelligence official said on Thursday.

The operative, Maksim Vladimirovich Filchenkov, 49, had been working undercover in Japan as an employee of the Russian state airline Aeroflot. Mr. Filchenkov’s role had been the focus of a Times investigation into how Russia exploited Japan’s weak espionage laws.

Mr. Filchenkov’s departure was first reported by Yomiuri Shimbun, a major national newspaper in Japan. The newspaper said the Russian exited Japan after The Times published its investigation on July 12. The Ukrainian official who confirmed the spy’s departure did so on condition of anonymity because he was not authorized to discuss intelligence publicly.

The Russian spy’s presence in that country had frustrated Ukraine, which had repeatedly warned that, despite Japan’s export restrictions and economic sanctions, its high-tech components were still being shipped to Russia. Ninety percent of Russian missiles and drones contain Japanese components, according to Ukrainian government estimates.

“This is definitely good news and it’s an important example of what has to be done,” said Sergiy Korsunsky, who served as Ukraine’s ambassador to Japan from 2020 to 2024. He said he had raised concerns with Japanese officials about their technology finding its way to the battlefield.

Mr. Filchenkov was part of a clandestine unit known as the 20th Directorate of Russia’s military intelligence agency, the G.R.U. Posing as diplomats or businesspeople, its officers work to buy or steal battlefield technology and smuggle it into Russia.