Russia’s security service said it received U.S. information about preparations for a possible terrorist attack and was taking action.
MOSCOW, RUSSIA — The U.S. Embassy in Moscow warned Saturday of what it called a credible threat of a mass-casualty event at the Tsaritsyno Museum Reserve, while Russia’s Federal Security Service said it had received information from the United States about preparations for a possible terrorist attack.
The embassy said the threat concerned the museum and park complex in southern Moscow on Oct. 31. It said the U.S. government was coordinating with Russian authorities on a response. The alert did not identify who was suspected of planning an attack, describe the nature of the possible threat or explain how the information was obtained.
Russia’s Federal Security Service, known as the FSB, later confirmed that information had been passed through established channels between the two countries. The agency said it had received information from U.S. partners about preparations for a terrorist attack in Moscow and that appropriate measures were underway. It did not publicly provide further details about a suspected group, possible method or specific intelligence behind the warning.
The Tsaritsyno Museum Reserve was temporarily closed and access to its park grounds was restricted, according to Russian state media reports citing law enforcement officials. The sprawling site, which includes a historic palace complex and landscaped park, is in the southern part of the Russian capital and is a well-known destination for residents and tourists.
The U.S. security alert told people to stay away from the Tsaritsyno site on Saturday, remain alert and avoid crowds. The embassy also advised Americans to monitor local information and remain prepared for further security developments. The warning was unusually specific in naming a location and a date for the potential threat.
The alert came against the backdrop of an earlier U.S. warning before the March 22, 2024, attack at Crocus City Hall outside Moscow. On March 7 of that year, the U.S. Embassy warned that extremists had imminent plans to target large gatherings in Moscow, including concerts. The United States also shared threat information directly with Russian authorities.
Gunmen later attacked Crocus City Hall, killing more than 140 people and injuring hundreds. An affiliate of the Islamic State group claimed responsibility. U.S. officials said at the time that intelligence supported the Islamic State claim, while Russian officials later raised allegations of possible Ukrainian involvement. Ukraine denied involvement, and U.S. officials rejected claims that Kyiv was responsible.
The 2024 attack increased scrutiny of how warnings between Washington and Moscow are handled during a period of severe tension between the two governments. Despite their broader political confrontation, Russian and U.S. security agencies have maintained channels that can be used to exchange information about terrorism threats.
As of Saturday, Russian authorities said they were acting on the latest U.S. information, and the Tsaritsyno grounds remained subject to access restrictions. Public statements reviewed Saturday did not identify suspects or announce arrests, and no attack connected to the warning had been reported.
Author note: Last updated October 31, 2026.