The United States Ambassador to Russia Michael McFaul was summoned by the Foreign Ministry on Wednesday over Moscow’s claim that it caught a U.S. diplomat disguised in a blond wig trying to recruit a counter-intelligence officer for the CIA.

Mr. McFaul entered the Ministry’s building in central Moscow in the morning and left half an hour later without saying a word to journalists waiting outside the compound.

Russian security officials reported on Tuesday that they briefly detained Ryan Fogle, a third secretary at the U.S. Embassy, who was carrying special technical equipment, disguises, written instructions and a large sum of money. Mr. Fogle was later handed over to U.S. Embassy officials.

Mr. McFaul has had a tough run in Moscow since he took office in January 2012. He provoked the ire of Russian officials when one of his first acts was to invite a group of Opposition activists and rights advocates to the Embassy. Later, Mr. McFaul alleged that Russia had offered money to the leader of Kyrgyzstan for removing a U.S. base from its soil.

Mr. Fogle’s detention appeared to be the first case of an American diplomat publicly accused of spying in about a decade.

The State Department would only confirm that Mr. Fogle worked as an Embassy employee, but wouldn’t give any details about his employment record or responsibilities in Russia. The CIA declined comment.

The Russian Foreign Ministry promptly declared Mr. Fogle persona non grata and ordered him to leave Russia immediately. He has diplomatic immunity, which protects him from arrest.

Despite the end of the Cold War, Russia and the United States still maintain active espionage operations against each other. Last year, several Russians were convicted in separate cases of spying for the U.S. and sentenced to lengthy prison sentences.

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