"The Saudi situation is, geopolitically, not good news," said Kengo Suzuki, chief currency strategist at Mizuho Securities Co. in Tokyo.
The Bloomberg Dollar Spot Index advanced 0.3 percent to 1,236.35. The yen was at 120.39 per dollar after earlier reaching 120.04. It touched 120.01 on Dec. 31, the highest since Oct. 22, and climbed 2.4 percent last month.
Caixin Media and Markit Economics release China's December manufacturing purchasing managers' index, and economists forecast it will show a 10th-straight month of shrinking.
The official purchasing managers index edged up to 49.7 last month from a three-year low of 49.6 in November, the National Bureau of Statistics said last Friday.
That was the official gauge's fifth month below 50 - the dividing line between contraction and expansion - the longest such streak since 2009.
- Bloomberg