Japanese shares slipped at Thursday's open but regained ground within the first half hour of trading after the Federal Reserve kept rates steady, even with crude prices climbing.
The Nikkei 225 fell 176 points or 0.3% to 61,258 before reversing its decline.
Fed Reserve Chair Warsh, in a press conference on Wednesday, stressed the decision reflected active policy commitment, not passivity, in fighting inflation.
Brent Crude held near $90 after Trump's Iran strike threats and a drop in US inventories fueled the biggest rally in over two weeks.