The benchmark Nikkei 225 index slipped 0.12 percent or 26.82 points to 21,660.28 while the broader Topix index was down 0.39 percent or 6.78 points at 1,718.52.

Share prices opened lower after Wall Street stocks sagged as Donald Trump announced on Twitter that missiles "will be coming" in response to an alleged chemical attack in Syria.

"It's Syria that dragged the market down but drops are limited," said Toshihiko Matsuno at the investor information division of SMBC Nikko Securities.

"For now, there are people who think an event involving military conflict would be a buying opportunity," he told AFP.

A year ago Trump ordered the US military to strike Syria with cruise missiles, which prompted only short-lived selling in markets, Matsuno noted.

"They are betting that selling would again be temporary," he said.

The dollar was trading at 106.93 yen against 106.80 yen in New York Wednesday afternoon.

In Tokyo trade, Sony dropped 1.36 percent to 5,200 yen as Panasonic lost 0.84 percent to 1,522.5 yen.

Carmakers were mixed. Honda fell 1.24 percent to 3,735 yen but Toyota rose 0.40 percent to 6,873 yen with Nissan unchanged at 1,122 yen.

Market heavyweight Fast Retailing, the operator of the Uniqlo clothing chain, jumped 2.06 percent to 46,900 yen. Shortly after the market closed, the firm upgraded its full-year forecast.