India, Nov. 2 -- Russia's Federal Security Service said on Sunday that it had detained a minor on suspicion of planning a terrorist attack at the Tsaritsyno Museum Reserve in southern Moscow, a day after the US Embassy issued a warning about a credible threat at the site. The agency said the information had come from American authorities through established channels of cooperation.

The arrest is the first public result of the warning issued by the US Embassy in Moscow on Saturday, which described a "credible threat of a mass casualty event" at the palace and park complex. The Russian authorities have not said whether the suspect had acquired weapons or moved beyond planning.

What Did The FSB Say About Suspect?

In a statement, the FSB s...