CHINA is storing up arms at an unnecessarily rapid rate at the same time as the United States is hacking back its military resources, posing a real threat to national security, according to former US defence secretary Mr Caspar Weinberger. In Hongkong on a whistle-stop tour yesterday, Mr Weinberger said: ''The rapidity with which China is acquiring arms from the old Soviet Union is an obvious source of concern. Russia in particular seems to be selling to very undesirable countries. ''It is puzzling to know why China is doing it. It has a large army and would only need modernisation if it was still facing a Soviet threat. But under the circumstances, we have to worry.'' He also cast doubt on US President Mr Bill Clinton's policy of whittling down the army, as this could threaten national security. ''The Gulf Crisis blew up very suddenly. The world is not really free of threat and I think the threats will increase if we are seen to be bent on a course of weakening ourselves and not able to do anything about it.'' Mr Weinberger, who served under presidents Mr Richard Nixon, Mr Gerald Ford and MrRonald Reagan, was embroiled in the Iran-Contra cover up when it was alleged he was concealing notes taken at key meetings. The then president Mr George Bush's decision to pardon him cancelled the trial - a move attacked by special prosecutor Mr Lawrence Walsh as inappropriate and preventing new evidence from coming to light. Mr Weinberger yesterday refused to discuss the affair. His own notes show he was opposed to the arms-for-hostages deal. Now publisher of Forbes magazine, the 75-year-old man's one-time aggression and sparky relations with cabinet colleagues has mellowed. China is no longer the red foe of American folklore, but Mr Weinberger is against pussyfooting round the emerging economic miracle the mainland has become. Dubbing the controversial sale of fighter planes to Taiwan an important act of friendship and support, he said America should not put fear of upsetting China above fostering relations with ''our great trading ally and friend''. ''There was always a worry that mainland China might overtake Taiwan and now I think that situation has been reversed. Taiwan's economy is so much stronger and more powerful than China's that it would be great folly if we continued to ignore the importance of our alliance with it or failed to help in any way we can,'' he said.