The losses extended falls on Tuesday and followed drops on Wall Street and in Europe as investors ran for cover, while stocks and currencies in developing Asian countries came under renewed pressure.
Adding to the tensions in the Middle East are concerns about a looming row in Washington over the US debt ceiling, which could leave the country in political deadlock.
Tokyo tumbled 1.51 per cent, or 203.91 points, to 13,338.46 and Sydney shed 1.05 per cent, or 54.0 points, to close at 5,087.2.
Emerging markets in Asia -- already seeing selling because of the expected wind-down of the US Federal Reserve's massive stimulus programme -- were mostly lower.
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Jakarta closed 1.48 per cent higher, but Kuala Lumpur was off 0.89 per cent and Bangkok lost 1.41 per cent.
Manila ended down 3.02 per cent, or 178.93 points, at 5,738.06 as traders grew jittery before the release of economic growth data on Thursday. However, it managed to pare earlier losses that saw it down almost six per cent.
"We are prepared. We have moved assets in place to be able to fulfil and comply with whatever option the president wishes to take," US Defense Secretary Chuck Hagel told the BBC on Tuesday.
The possibility of more turmoil in the oil-rich region saw crude prices extend gains.
New York's main contract, West Texas Intermediate for delivery in October, hit an intra-day high in Asia of USD 112.23. Brent North Sea crude for October spiked at USD 117.22.
On Wall Street, the Dow fell 1.14 per cent, the S&P 500 lost 1.59 per cent and the Nasdaq tumbled 2.16 per cent, while Paris and Frankfurt each lost more than two per cent.
In forex trade, the dollar sat at 97.38 yen, up from 97.01 yen late in New York but well down from levels above 98.00 yen in Tokyo on Tuesday.
The euro bought USD 1.3348 and 129.92 yen compared with USD 1.3391 and 129.88 yen.