The most-active soybean contract on the Chicago Board of Trade was down 0.2 percent at $9.22-3/4 a bushel as of 0242 GMT, having climbed to the highest since Dec. 12 at $9.27-3/4 a bushel on Monday.
Wheat futures slipped 0.2 percent to $5.16 a bushel and corn was up 0.2 percent at $3.83 a bushel.
"Soybeans have rallied but the market wants to see positive outcome from these trade talks before gaining further or sustaining these gains," said Phin Ziebell, agribusiness economist at National Australia Bank. "There is no shortage of beans, fundamentals do not really support of a rally in prices."
Chinese importers made their third large U.S. soybean purchase in the past month on Monday, as officials from both countries meet this week for the first face-to-face talks since agreeing to a 90-day trade war truce on December 1, two traders with knowledge of the deals said.
Chinese state-owned firms bought at least three cargoes of U.S. soybeans on Monday morning, or about 180,000 tonnes, the traders said. One of them said the total was closer to 15 cargoes, or about 900,000 tonnes.
U.S. Commerce Secretary Wilbur Ross predicted on Monday that Beijing and Washington could reach a trade deal that "we can live with" as dozens of officials from the world's two largest economies resumed talks in a bid to end their trade dispute.
Adverse weather conditions in Brazil for soybeans provided additional support to prices. Consultancy INTL FCStone cut its estimate of Brazil's soybean crop on Friday by about 4 million tonnes to 116.25 million tonnes due to a drought affecting some areas.