China has emerged as the most prolific intelligence threat to U.S. having engaged in corporate espionage, intellectual-property theft, and personnel information breaches going back decades. A naturalized U.S. citizen who immigrated from China has been sentenced to four years in prison after conspiring to act as a agent of the Chinese government, highlighting the broad reach of Beijing’s security service and strategy of co-opting immigrants for intelligence gathering, according to the Justice Department. The plea agreement and court filings announced Monday show China’s Ministry of State Security – the Communist-run country's intelligence service – used operative Peng Li as a...