The Kremlin said on Tuesday that Wall Street Journal reporter Evan Gershkovich had "violated Russian law" and been caught "red-handed" after the US State Department officially designated him as having been "wrongfully detained" by Russia.
Russia's federal security service (FSB) arrested Gershkovich last month on espionage charges widely decried as bogus by the White House, other Western countries, the Wall Street Journal, dozens of media organizations and human rights groups.
The United States' determination that he was "wrongfully detained" means that it believes he was targeted primarily because he is an American citizen, and its transfer of the case from the State Department to the office of the Special Envoy for Hostage Affairs raises the issue's political profile.
Asked about the US move on Tuesday, Kremlin spokesman Dmitry Peskov repeated Russia's position that Gershkovich broke the law.
"I don't understand what kind of innovations this new regime is introducing. As for what it means, I don't know," Peskov said of the designation. He said Gershkovich had "been caught red-handed and violated the laws of the Russian Federation," before adding: "This is what he's suspected of, but of course, the court will make a decision."
More than 99% of criminal cases in Russia end in a conviction for the prosecution and the country has long been criticized by rights monitors for a lack of judicial independence.
Russia has presented no evidence to support the case against Gershkovich, which is proceeding in secret because Russia says the case materials are confidential.
Next week, a court will hear an appeal from Gershkovich's legal team against an order that he be held in pre-trial detention at Moscow's Lefortovo prison until May 29.