U.S. President Donald Trump is taking his trade wars into a new realm likely to both extend them and make them harder to resolve.

With his crackdown on Chinese telecommunications giant Huawei Technologies Co. and a new directive targeting European and Japanese carmakers, his administration is displaying its penchant to invoke U.S. national security in the broadest way possible. In doing so Trump is exploiting a loophole in global trading rules and doing what his predecessors spent years urging China and others not to at the risk of opening a protectionist Pandora's box.

The administration's willingness to bend the rules on national security grounds is evident in a proclamation Trump issued on Friday that labeled imported cars a threat to U.S. national security and called for reducing imports. It also delays the imposition of auto tariffs for 180 days while U.S. officials negotiate with the EU and Japan to reduce their exports of automobiles and parts to the U.S.