USD/JPY changed hands at 112.22, down 0.14%, while AUD/USD traded at 0.7621, flat. EUR/USD was down 0.04% to 1.213.
The U.S. dollar index, which measures the greenback's strength against a trade-weighted basket of six major currencies, was last quoted flat at 95.67.
Risk sentiment took a hit after explosions tore through the departure hall of Brussels airport on Tuesday morning killing at least 26 people and injuring 35 others and a second blast struck a metro station in the capital shortly afterwards.
The blasts at the airport and metro station occurred four days after the arrest in Brussels of a suspected participant in November militant attacks in Paris that killed 130 people.
As well this week, San Francisco Fed President John Williams and Atlanta Fed President Dennis Lockhart said in separate news reports that a rate hike could come as early as next month. However, neither are voting members of the Federal Open Market Committee.
On Tuesday, Chicago Fed President Charles Evans said as long as inflation is "underrunning" the Federal Reserve's 2% target, there is time to assess the global risks and hold off on raising rates again, as it is critical to get inflation up and even risk going above that level.
While it is true the economy is close to full employment, with unemployment at 4.9% and expected to fall further this year, "we have room to see how this plays out," Evans said in a speech to the City Club of Chicago.
Evans, who is not a voter on the policy-setting Federal Open Market Committee this year, said the FOMC's "cautionary pause" after the initial rate increase in December was the appropriate response to the "bumpy" start to 2016 and the risks to global economic and financial conditions.
The U.S. central bank surprised markets last week by cutting its rate hike projections more than expected, down from four to two in 2016, citing the potential impact from weaker global growth and financial market turmoil on the U.S. economy.
Overnight, the dollar remained moderately against the other major currencies on Tuesday, as investors were cautious after a series of explosions in Brussels killed at least a 34 people and injured over 100.
Safe-haven demand strengthened after at least 34 people were killed in a series of explosions in Brussels on Tuesday morning, with two blasts at the airport and another at a metro station in the heart of the EU quarter an hour later.
On Tuesday, Reserve Bank of Australia Governor Glenn Stevens said in a speech that Australia's economy was "adjusting quite well" to lower commodity prices and had more fiscal and policy scope to respond to a global downturn than most countries.