WASHINGTON

The US State Department on Thursday criticized Russia's decision to declare two American diplomats “persona non grata,” and pledged to respond appropriately.

"This unprovoked expulsion of our diplomatic personnel is wholly without merit," spokesman Matthew Miller told reporters. "We regret that Russia has taken this path and you can certainly expect that we will respond appropriately to their actions.”

Miller said Moscow has chosen confrontation and escalation over constructive diplomatic engagement.

The Russian Foreign Ministry said it summoned Ambassador Lynne Trace and conveyed to her strong protests regarding "the incompatibility with the diplomatic status of the actions of the first secretary of the US Embassy, Jeffrey Sillin, and the second secretary of the Embassy, David Bernstein."

"These persons conducted illegal activities, maintaining contact with Russian citizen Robert Shonov, accused of 'confidential cooperation' with a foreign state," it added.

In late August, Russia’s Federal Security Service (FSB) said it wanted to question Sillin and Bernstein about their allegedly trying to get Rostov to gather intelligence on the Ukraine war.

Rostov was formerly employed by the US Consulate in Vladivostok in the Russian Far East.

At the time, the US denied the allegation, with Miller calling them “wholly without merit” and part of an effort “to intimidate and harass our employees.”