WASHINGTON — In the most comprehensive sanctions against Russia since the end of the Cold War, President Obama on Monday froze the US assets of seven Russian officials, including top advisers to President Vladimir Putin, for their support of Crimea’s vote to secede from Ukraine.
Obama said he was moving to ‘‘increase the cost’’ to Russia, and he warned that more people could face financial punishment unless there is a diplomatic solution to the crisis.
The Treasury Department also is imposing sanctions on four Ukrainians — including former President Viktor Yanukovych and others who have supported Crimea’s separation — using existing authority under a previous Obama order.
Those Obama targeted in his sanctions order Monday are key political players in Russia and also responsible for tightening of human rights and civil liberties in the country.
The seven subjects of the president’s order include: Vladislav Surkov, a Putin aide; Sergey Glazyev, a Putin adviser; Leonid Slutsky, a state Duma deputy; Andrei Klishas, member of the Council of Federation of the Federal Assembly of the Russian Federation.
Also targeted were Valentina Matviyenko, head of the Federation Council; Dmitry Rogozin, deputy prime minister of the Russian Federation; and Yelena Mizulina, a state Duma deputy.
Those targeted will have all US assets frozen and no one in the United States can do business with them.
The European Union announced sanctions and travel restrictions targeting 21 people, including Slutsky, but avoided going after figures in the Russian elite such as Surkov, Glazyev, Matviyenko, and Rogozin, because they were concerned about poking too directly at the Russian president in a way that would make it harder for him to back down later.
Altogether, the European list included 10 Russian politicians, seven pro-Russian Crimeans, three Russian military officers in Crimea and the former head of Ukraine’s Black Sea Fleet, who defected to Russia this month.
The four newly targeted by the Treasury Department are: Yanukovych, who fled Ukraine for Russia and has supported the dispatch of Russian troops into Ukraine; Viktor Medvedchuk, the leader of Crimea separatist group Ukrainian Choice and a close friend of Putin; Sergey Aksyonov, prime minister of Crimea’s regional government; and Vladimir Konstantinov, speaker of the Crimean Parliament
Senator John McCain, Republican of Arizona, back from a weekend trip to Kiev, said Obama was not going far enough.
‘‘I think Vladimir Putin must be encouraged by the absolute timidity,’’ McCain said on MSNBC.
He said of Obama’s response, ‘‘I don’t know how it could have been weaker, besides doing nothing — seven people being sanctioned after naked aggression has taken place.’’
White House spokesman Jay Carney did not rule out sanctions against Putin himself.
‘‘We have the authorities to more broadly identify individuals and entities in the future, and we will do that as necessary if the costs to Russia need to be increased,’’ Carney said.
The sanctions were expected after residents in Crimea voted overwhelmingly Sunday in favor of the split. Crimea’s Parliament on Monday declared the region an independent state.