WASHINGTON (Reuters) - The United States is aware of a higher-than-usual level of activity by Chinese bomber planes, signaling a possible heightened state of readiness, U.S. officials told Reuters on Thursday, but downplayed concerns and left open a range of possible reasons. None of the officials, who spoke on condition of anonymity, suggested alarm or signaled that they knew the precise reason for such Chinese activity. Those possibilities include defensive exercises or Chinese concerns over North Korea. U.S. officials have long speculated that North Korea could soon stage another nuclear test or carry on with missile tests. The comments to Reuters came before U.S. President Donald Trump on Thursday cited, without explanation, “some very unusual moves” that he said had been taken over the last two or three hours. It was not immediately clear what he was referring to.  Trump was speaking about Chinese activities to put pressure on Pyongyang when he said:  “Some very unusual moves have been made over the last two or three hours and I really have confidence that the (Chinese) president will try very hard. We don’t know whether or not they’re able to do that but I have absolute confidence that he will be trying very very hard,” Trump said. Trump has taken a hard line with North Korean leader Kim Jong Un, who has rebuffed admonitions from sole major ally China and proceeded with nuclear and missile programs in defiance of U.N. Security Council sanctions. 
U.S. sees increased activity by Chinese bomber aircraft: officials