China’s pledge to choke off shipments of rare earth elements could wreak havoc on tech giants like Apple and Tesla as well as big US military contractors – and experts called it a major bargaining chip as Beijing haggles with President Trump over tariffs.US companies and investors alike are scrambling to assess the impact of Beijing’s announcement that foreign entities must obtain special licenses beginning Dec. 1 to export products containing more than 0.1% of rare earth metals and magnets originating in C ...