The Treasury Department auctioned $24 billion in 3-year notes at a high yield of 1.525 percent. The bid-to-cover ratio, an indicator of demand, was 2.62.
Indirect bidders, which include major central banks, were awarded 51.8 percent. Direct bidders, which includes domestic money managers, bought 8.3 percent.
U.S. government debt prices were mostly higher on Monday as comments over the weekend from U.S. Secretary of State Rex Tillerson appeared to retreat from expectations of a campaign to remove Syrian president Bashar Assad.
The U.S. launched a missile strike against a Syrian airfield late Thursday in response to an alleged chemical attack which killed several Syrian civilians.
Investors will be keenly watching events in Italy on Monday, where G7 foreign ministers will begin a two-day meeting and it is hoped that Tillerson may provide more clarity on Syria and an array of international issues.