Adds Descartes comment in paragraphs 4 and 9, port-level declines in paragraph 5, China import composition in paragraph 6

By Lisa Baertlein

LOS ANGELES, June 9 (Reuters) - U.S. seaborne imports of goods from China dropped 28.5% year-over-year in May, the sharpest decline since the pandemic, as President Donald Trump's 145% tariffs took hold, supply chain technology provider Descartes DSG.TO said on Monday.

China is the top U.S. supplier of goods that enter through seaports, including the nation's busiest in Los Angeles/Long Beach. Domestic businesses ranging from retailer Walmart WMT.N to automaker Ford F.N depend on those goods to operate.

Overall U.S. seaborne imports in May tumbled 7.2% from the year earlier to 2.18 million 20-foot equivalent units - snapping a streak of near-record increases fueled by companies frontloading goods to avoid higher duties.

"The effects of U.S. policy shifts with China are now clearly visible in monthly trade flows," Descartes said in a statement.

West Coast ports are more dependent on China trade and bore the brunt of the declines. From April to May, the nation's busiest seaports in Long Beach and Los Angeles experienced steep drops in goods from China, 31.6% and 29.9%, respectively, Descartes said.

Top imports from China included furniture, bedding, plastic goods, machinery, toys and sporting goods.

The United States and China agreed to a 90-day pause on punitive tit-for-tat tariffs last month. U.S. and Chinese officials met in London on Monday to defuse the high-stakes trade dispute between the world's largest economies.

Port executives and shipping consultants expect volume from China to rebound during the tariff truce, albeit at a more moderate level. That's because the U.S. lowered the tariff for many goods from China to 30% during the pause.

"China-origin imports may continue to soften in the months ahead as importers reassess sourcing strategies amid rising landed costs," Descartes said.

(Reporting by Lisa Baertlein in Los Angeles; Editing by Rod Nickel and Cynthia Osterman)

((lisa.baertlein@thomsonreuters.com; +1 310-491-7241; Reuters Messaging: lisa.baertlein.thomsonreuters.com@reuters.net))