The Nikkei fell 0.62 percent by 8:36 a.m. as the safe-haven yen strengthened in the wake of renewed political risk.
Equities in Asia lost ground on Wednesday, with Dow futures tumbling and the safe-haven yen climbing amid political and legal turmoil surrounding US President Donald Trump.
"Investors are deeply concerned that all the political noise will morph into economic risk as the political back-fence talk, speculation and dirty laundry could detract from Trump's key agenda: Tax reform," Stephen Innes, senior trader at OANDA, said in a note on Wednesday.
The Dow Jones industrial average futures for June tumbled 121 points to 20,813 by 8:40 a.m. HK/SIN, compared with the index's close at 20,979.75 as risk-off sentiment struck the market.
The Nikkei fell 0.62 percent by 8:36 a.m. as the safe-haven yen strengthened in the wake of renewed political risk. The dollar was fetching just 112.57 yen at 8:02 a.m. HK/SIN, an around two-week low.
Across the Korean Strait in South Korea, the Kospi was down 0.35 percent. Australia's S&P/ASX 200 dropped 0.81 percent.
The euro rose to a six-month high as political event risk receded from the continent. The common currency last traded against the dollar at $1.1088, compared with levels under USD 1.09 last week.
In the US, Trump defended his actions, saying on Twitter that he had "the absolute right" to share classified intelligence with Russian officials. The President's tweets came after his national security adviser told the media that the incident reported by the Washington Post did not take place.
Additionally, a New York Times report on Tuesday, later confirmed by NBC News, Trump allegedly asked then-FBI Director James Comey, who Trump later fired, to stop investigating now-fired national security adviser Michael Flynn.
Elsewhere, calls grew for a wider investigation as a key House Republican asked the FBI on Tuesday for any records it has on communications between former FBI Director James Comey and President Donald Trump.
Chinese tech stocks are also likely to be in the spotlight, with the Hong Kong-listed Tencent expected to report earnings today. Nasdaq-listed Weibo and Sina released their earnings for the first quarter in the US on Tuesday. Sina rose sharply after earnings per share came in at USD 0.50 per share, well above FactSet estimates of USD 0.17.
In currency news, the dollar continued to sag. The dollar index, which measures the greenback against a basket of rival currencies, was down at 98.087 at 8:38 a.m. HK/SIN, compared with levels above 99 last week.
"While there is no particular headline behind the move, a likely combination of slipping US yields, softer oil prices and heightened political uncertainty in Washington are providing traders with this morning's toxic dollar elixir. While the market is fishing for a base this morning, momentum does suggest there is the potential for a deeper US dollar selloff," OANDA's Innes said.
The Aussie strengthened against the dollar for a sixth straight session to trade at USD 0.7412.Overnight in the US, the Dow Jones industrial average fell 2.19 points, or 0.01 percent to close at 20,979.75 and the S&P 500 slipped 1.65 points, or 0.07 percent, to end at 2,400.67, while the Nasdaq advanced 20.20 points, or 0.33 percent, to close at 6,169.87 after touching an intraday record high.