U.S. crude gave up early gains in Asia on Monday and fell following the 9th ballistic missile test by North Korea this year ahead of a day with China, the U.S. and U.S. on public holidays.
U.S. West Texas Intermediate crude's July contract fell 0.36% to $49.62 a barrel. Elsewhere, on the ICE Futures Exchange in London, Brent oil for July eased 0.32% at $52.34 a barrel.
Last week, oil futures settled higher on Friday, rebounding from the prior session's near 5%-drop as traders continued to digest the latest extension of production cuts from OPEC and some non-OPEC members.

Oil prices tumbled on Thursday as the extension of output curbs by OPEC and other producing countries disappointed investors who had hoped for larger cuts, leading to the biggest daily percentage slide in crude prices since early March.
At Thursday's meeting in Vienna, the Organization of the Petroleum Exporting Countries and some non-OPEC producers agreed to extend supply cuts of 1.8 million barrels per day until the end of the first quarter of 2018.
While OPEC's move had been widely expected, some oil market investors had hoped producers would agree to longer or deeper cuts to drain a global glut of crude supplies.
The cartel next meets in November.
So far, the production-cut agreement has had little impact on global inventory levels due to rising supply from producers not participating in the accord, such as Libya and Nigeria, and a relentless increase in U.S. shale oil output.
Data from energy services company Baker Hughes showed on Friday that U.S. drillers last week added rigs for the 19th week in a row, the second-longest such streak on record, implying that further gains in domestic production are ahead.
The U.S. rig count rose by 2 to 722, extending an 11-month drilling recovery to the highest level since April 2015.
