Top Russian security officials claimed Tuesday that Ukraine and the West were partly responsible for the deadly concert hall attack outside of Moscow late last week, which saw camouflaged gunmen indiscriminately kill at least 139 people and wound dozens more. The head of Russia's Federal Security Service (FSB) Alexander Bortnikov said that while those who "ordered" the attack had not yet been identified, the assailants had intended to flee to Ukraine, where they would have been "greeted as heroes.""We believe the [attack] was prepared both by radical Islamists and, of course, facilitated by Western special services, and Ukraine's special services have a direct connection to this," Bortnikov was quoted as saying by state-run media.So, too, did Nikolai Patrushev, who heads Russia's Security Council, echo Bortnikov's claim that Kyiv was involved in the attack, telling the Telegram news channel Shot in a video: "Of course, it was Ukraine." Russian President Vladimir Putin said Monday night that "radical Islamists" were behind the mass killing, but otherwise doubled down on his previous claim that Ukraine may have somehow been involved and suggested that Washington was allegedly trying to cover it up.Putin had said before that the gunmen behind Friday's attack had driven their getaway car toward the Ukrainian border before being detained the following morning.The Islamic State’s affiliate ISIS-K has claimed responsibility for the attack, the deadliest in Russia since the 2003 Beslan school siege, and social media channels linked to the militant group have published graphic videos of the gunmen committing the mass killing at Crocus City Hall.Russian authorities have detained 11 people in connection to Friday's attack, though the identities of only eight of the suspects are currently known.Following Patrushev's and Bortnikov's remarks on Tuesday, Ukrainian presidential adviser Mykhailo Podolyakaccused the two Russian officials of "spreading lies."AFP contributed reporting.