A deal meant to power Saudi Arabia's energy future is instead fuelling fears of a new nuclear race in the Middle East. US President Donald Trump has signed a landmark 30-year nuclear agreement with Riyadh that could allow the kingdom to enrich uranium for power reactors, according to several US media outlets.The agreement will allow American companies to provide technology and expertise for Saudi Arabia's civilian nuclear programme, giving US firms access to what could become one of the world's biggest nuclear energy markets. But the commercial opportunity has been overshadowed by concerns that the deal weakens long-standing safeguards against…