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President Obama said Thursday that new sanctions targeting Russia are "teed up" in the wake of a fresh warning by the Russian foreign minister that attacks on Russian citizens or interests in Ukraine would bring a firm response.

Obama said Russia has not abided by the spirit or the letter of an agreement reached in Geneva last week that aimed to ease tensions in eastern Ukraine. He said Russia has failed to halt aggression by pro-Russian militants in the region.

Still, he cautioned that the United States needs to secure the support of allies to ensure that additional economic pressure is even applied. He conceded that new sanctions may not change Russian President Vladimir Putin's intentions and that the crisis in Ukraine may not subside.

"How well they change his calculus depends on the cooperation of other countries," Obama said during a news conference with Prime Minister Shinzo Abe during his first stop of a four-country tour of Asia.

The president did not put a timeline on when sanctions could be applied, saying only it was a matter of days, not weeks.

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    "It's important to emphasize that throughout this process our goal has been to change Mr. Putin's calculus, that our preference is to resolve this diplomatically, that sanctions hurt Russia more than anybody else but they are disruptive to the global economy," Obama said.

    Meanwhile, Russia's foreign minister warned Wednesday that attacks on Russian interests in Ukraine would prompt a firm response and drew a comparison to the circumstances that opened the war with Georgia in 2008.

    "Russian citizens being attacked is an attack against the Russian Federation," Foreign Minister Sergey Lavrov said, a day after Ukraine announced it was re-launching a campaign against pro-Russian insurgents occupying government facilities in the mostly Russian-speaking east.

    "If we were attacked we could certainly respond," Lavrov said, speaking on the Kremlin-funded satellite TV channel RT.

    Lavrov's warning came as the Russian Foreign Ministry issued a separate statement demanding that Ukraine pull its armed forces out of the crisis-ridden region.

    "If our interests, our legitimate interests, the interests of Russians have been attacked directly, like they were in South Ossetia, I do not see any other way but to respond in full accordance with international law," Lavrov said, referring to the 2008 war that led to the breaking away of the Georgian republic of South Ossetia.

    The Russian warnings came as an accord reached last week in Geneva to defuse the Ukraine crisis continued to crumble, with pro-Russian insurgents in the east defying calls for all sides to disarm and to vacate the buildings they are occupying.

    The White House had initially planned to impose new sanctions on Russia last week, but delayed the move after Russia's foreign minister signed the Geneva deal, two American officials who took part in the talks told The Wall Street Journal.

    U.S. officials told the newspaper the new sanctions being developed will focus on a wide range of Russian officials, business "cronies" close to Putin, and their companies. The EU is expected to follow with additional sanctions targeting another group of Russian and Ukrainian officials, according to the report.

    On Tuesday, Ukraine's acting president, Oleksandr Turchynov, ordered resumption of an "anti-terrorist operation" against the pro-Russia forces. However, the highly publicized move produced little action on the ground Wednesday.

    Police cleared the city hall in a southeastern Ukrainian city of pro-Russian protesters who had been occupying it for over a week, Interior Minister Avakov said Thursday, but local police officials and protesters presented quite another picture of what happened.

    Avakov wrote in a Facebook post on Thursday that the city hall in Mariupol "has been freed to resume work," but did not describe the action.

    However, Yulia Lasazan, a spokeswoman for Mariupol's police department, told The Associated Press that about 30 men masked men armed with baseball bats stormed the building in the early hours on Thursday and started beating the protesters. It was not clear why the protesters, some of whom were believed to be armed, did not offer resistance but called the police instead.

    Five people were taken to a hospital, Lasazan said.

    The crisis in Ukraine has provoked clear anxiety in Western Europe. Poland, which borders Russia and Ukraine, conducted its first major security exercise in decades on Wednesday.

    A U.S. Army company of about 150 soldiers from the 173rd Airborne Brigade Combat Team based in Vicenza, Italy, participated in the exercises in Poland. Additional Army companies will head to Estonia, Latvia and Lithuania and are expected to arrive by Monday for similar land-based exercises in those countries.

    Pentagon press secretary Rear Adm. John Kirby said Tuesday that the exercises will last about a month, and initially involve about 600 troops.

    Under the current plan, U.S. troops would rotate in and out of the four countries for additional exercises on a recurring basis.

    "We're looking at trying to keep this rotational presence persistent throughout the rest of this year," Kirby told reporters, adding that over time the exercises could expand to other countries.

    The exercises are part of an effort announced last week by Defense Secretary Chuck Hagel aimed at reassuring NATO allies of America's commitment to the region's defense.

    Meanwhile, Dutch, British and Danish fighter jets scrambled after a pair of Russian bombers approached their airspace over the North Sea on Wednesday. The Russian TU-95 Bear jets were escorted by the NATO members' aircraft until they departed.

    And the presidents of four post-Soviet republics and Ukraine's foreign minister were meeting in Prague with EU nations Thursday to try to figure out how to stop Russia from blocking their increased ties.

    The Associated Press contributed to this report.