WASHINGTON, Nov 29 (Reuters) - China will likely have a stockpile of 1,500 nuclear warheads by 2035 if it continues with its current nuclear buildup pace, according to a report released by the Pentagon on Tuesday.The figure underscores mounting U.S. concerns about China's intentions for its expanding nuclear arsenal, even though the projections do not suggest China is accelerating the pace of its already-brisk warhead development."They've got a rapid buildup that is kind of too substantial to keep under wraps," a senior U.S. defense official said during a news briefing on the Pentagon's annual report on China's military."It does raise questions about whether they're kind of shifting away from a strategy that was premised on what they referred to as a lean and effective deterrent."read moreThe report reiterated concern about increasing pressure by Beijing on self-ruled Taiwan, an island China sees as a breakaway province."