Russia's Putin offers sympathy to American people MOSCOW, Sept 11 (Reuters) - Russian President Vladimir Putin expressed sympathy and anger over attacks on U.S. targets on Tuesday, summoning security chiefs and calling for a coordinated international response to terrorism. Russian media said several security bodies went on higher alert after two hijacked aircraft smashed into the World Trade Center in New York and another crashed at the Pentagon in Washington. In a "Dear George" telegram to President Bush, Putin said "barbarous terrorist acts aimed against wholly innocent people cause us anger and indignation." "I ask you to pass on our deepest sympathies to the relatives of the victims of this tragedy, and the entire suffering American people. We understand their sorrow and pain as Russia has also suffered from terrorism," he wrote. "There is no doubt that such an inhuman act must not go unpunished. The entire international community should unite in the struggle against terrorism," he wrote to Bush. ATTACKS "A BRAZEN CHALLENGE" In a televised message, he called the attacks "a brazen challenge to all mankind, at least all civilised mankind." "We know from our own experience what terrorism is," he said, standing in a Kremlin office. "We understand the feelings of the American people better than anyone. I want to tell the American people in Russia's name, 'We are with you. We fully and wholeheartedly share and feel your pain. We support you'." Kremlin spokesman Alexei Gromov said Putin was immediately informed of the attacks and described them as a "terrorist act, this terrible tragedy." Television pictures issued by the Kremlin showed Putin meeting with top security officials. A U.S. embassy spokesman said "precautionary measures" had been taken, with public areas of the embassy closed on Wednesday along with a school attended mostly by foreign children. The embassy spokesman said diplomats saw "no credible threat to U.S. citizens in Russia." But they were asked to exercise "extreme caution and adopt a very low profile, not drawing attention to themselves, until the extent of attacks and danger to Americans can be evaluated." Interior Minister Boris Gryzlov said all measures were being taken to "defend citizens against possible terrorist acts." Defence Minister Sergei Ivanov broke off a trip to southern Russia to return to Moscow. Interfax news agency said members of Putin's personal security service had been ordered to return to their posts. The foreign ministry said the air force had cancelled military flights over the Atlantic, Pacific and Arctic Oceans in response to the attacks, cutting short war games that began on Monday and had been due to run until Thursday. Russia's anti-aircraft force was also placed on higher alert and Itar-Tass news agency quoted police as saying extra checks had been imposed on the baggage of people using Moscow's four main airports. Vehicles near the airports were being checked. Interfax said Emergencies Minister Sergei Shoigu had offered to send help to deal with the aftermath of the attacks.