S&P 500 e-minis were down 10.25 points, or 0.41 percent, with 217,904 contracts traded.
Analysts warned the softening dollar could test June's low of 108.82 yen and even the 2017 trough of 108.13 yen.
Trading conditions changed drastically late in the USA trading session on geopolitical concerns involving North Korea.
U.S. officials on Sunday played down the risk of an imminent war with North Korea.
Investor sentiment got a boost after key USA officials on Sunday played down the risk of an imminent war with North Korea, which had wiped out almost $1 trillion from global equity markets last week.
The Dow edged down 33.08 points or 0.2 percent to 22,085.34, the Nasdaq dipped 13.31 points or 0.2 percent to 6,370.46 and the S&P 500 slipped 5.99 points or 0.2 percent to 2,474.92.
Trump warned North Korea again on Thursday not to strike Guam or USA allies, saying his earlier threat to unleash "fire and fury" on Pyongyang if it launched an attack may not have been tough enough.
With the tense mood pushing European shares down for a third day [EU] and Wall Street set to fall again [.N], global stocks .world were on course for their worst week since Donald Trump won November's USA presidential election.
Geopolitical tensions are not the only thing analysts are looking for as a trigger for a selloff in a market that has not had a major pullback in 18 months.
Geopolitical risks can boost demand for assets considered safe-haven investments, such as gold.
The euro was down 0.4 percent at $1.1733, helping push the dollar index, which measures the greenback against a basket of currencies, up 0.4 per cent.
Snap Inc's (SNAP.N) stock ended up 6.5% after hitting a record low early in the session, as big investors reported their stakes in the social media company.
"Amid tensions in the worldwide arena, it's hard to seek higher prices ahead of three days of holidays", Kawaguchi added.
The dollar was also helped by comments from New York Federal Reserve President William Dudley, who told the Associated Press he would favour a third increase in Fed interest rates this year if the economy developed as he expected.
Brent crude, the global benchmark, was last down 2 cents at US$50.71 a barrel. "Of course, it's all come at a time when share markets are due for a correction, so North Korea has provided a ideal trigger."NEW CUBAN CRISIS?South Korea's KOSPI .ks11 fell 1.8 percent to an 11-1/2-week low, but its losses for the week are a relatively modest 3.2 percent".