BEIJING, Jan 18 (Reuters) - China"s aviation regulator on Tuesday suspended another eight incoming U.S. flights by U.S. airlines, bringing the total cancellation this year to 84, based on a Reuters tally. The Civil Aviation Administration of China ordered United Airlines (UALCO.UL) to suspend four more flights from San Francisco to Shanghai over COVID-19 cases, while ordering Delta Air Lines (DAL.N) to cancel two flights from Seattle to Shanghai from the week of Jan. 31. Two Dallas-to-Shanghai flights from American Airlines (AAL.O) will be cancelled from Feb. 21 over COVID-19 cases, the regulator said.