US President Donald Trump ordered a probe Tuesday that may result in tariffs on critical minerals, rare-earth metals and associated products such as smartphones, in an escalation of his dispute with global trade partners.Trump has upended markets in recent weeks with his sweeping on-off levies, and this investigation could see him impose further tariffs if it shows that imports of critical minerals and their derivatives endanger US national security.China dominates global supply chains for rare metals.Without naming any other countries, the order says that the United States is dependent on foreign sources that "are at risk of serious, sustained, and long-term supply chain shocks."It states that this dependence "raises the potential for risks to national security, defense readiness, price stability, and economic prosperity and resilience."The imports targeted include so-called critical minerals like cobalt, lithium and nickel, rare-earth elements, as well as products that partly require these resources, such as electric vehicles and batteries.The order states that critical minerals and their derivatives are essential for US military and energy infrastructure, noting their use in jet engines, missile guidance systems and advanced computing, among others.The Department of Commerce will have up to 180 days to deliver its report to Trump, the order says, adding that any recommendations for action should consider the imposition of tariffs.It follows a similar "national security" investigation that Trump ordered Monday into pharmaceutical imports, and another on semiconductors and chip-making equipment.The process is based on a 1962 law that was seldom used before Trump, during his first 2017-2021 term, called on it to justify imposing taxes on steel and aluminum imports.The US president again resorted to this law, known as Section 232, to reintroduce in mid-March tariffs of 25 percent on steel and aluminum, and on automobiles.Trump has slapped new tariffs on friend and foe since returning to the presidency this year in a wide-ranging but often chaotic attempt to reorder the world economy by using levies to force manufacturers to relocate to the United States.