By Phil Stewart WASHINGTON (Reuters) - Chinese military spending exceeded $145 billion last year as it advanced a program modernizing an arsenal of drones, warships, jets, missiles and cyber weapons, the Pentagon said on Thursday, offering a far higher figure than Beijing's official tally. The Pentagon's estimate, using 2013 prices and exchange rates, was 21 percent above the $119.5 billion figure announced by China. China claims almost the entire oil- and gas-rich South China Sea and dismisses competing claims from Taiwan, Brunei, Vietnam, the Philippines and Malaysia. Japan also has a territorial dispute with China over islands in the East China Sea.