The Nikkei 225 Index closed 1% lower, snapping a three-day winning streak that had pushed the gauge to the highest since February 20. The broader Topix lost 0.6%.
The Israel-Iran conflict entered its seventh day, and U.S. President Donald Trump was ambiguous about whether Washington would join in bombardment of Iran’s nuclear sites.
“Heightened tensions in the Middle East continue to cool investor sentiment, with the downside appearing to widen,” said Nomura strategist Fumika Shimizu.
There were 62 advancers in the Nikkei index against 159 decliners. The largest percentage losses in the index were Trend Micro, down 8.4%, followed by Screen Holdings which skidded 4%.
Nippon Steel was among the top gainers, rising 2.3% after completing its long-awaited $14.9 billion acquisition of U.S. Steel.