Japan's key inflation gauge ticked up in February, putting the Bank of Japan halfway to its goal of 2 percent. Yet a strengthening yen and the threat of a global trade war underscore the central bank's vulnerability to global markets and events.

The core consumer price index, excluding volatile fresh food prices, rose 1 percent from a year earlier and picked up from a 0.9 percent rise in January, according to the Ministry of Internal Affairs and Communications.

Energy-related costs including electricity fees and gasoline prices continued to be the main driver behind the gains, pushing the index to its largest on-year growth since a 2.2 percent rise in March 2015. Stripping out the effect of a consumption tax hike in 2014, the increase was the largest since August of that year.