According to officials, on Feb. 11, Estonia deported Russian citizen Andrei Zhuravlyov.
Authorities said Zhuravlyov had been intended to collect intelligence in Ida-Viru County on behalf of Russian security services.
They added that such activity could form part of preparations for hybrid attacks.
The deportation was aimed at preventing the activities of Russian intelligence services and averting potentially serious consequences, the Security Police said.
Zhuravlyov had been residing in Estonia on the basis of a residence permit but spent most of his time in Russia, ERR reported.
On Jan. 16, Estonia deported another Russian citizen, David Arutyunyan, who had spread Kremlin propaganda on social media, praised the Russian National Guard and displayed service in the Russian army. His activities posed a real and long-term threat to the security of Estonia and other Schengen countries, according to the Security Police.