The largest exchange-traded fund to track Russia's equity market tumbled on Wednesday, following multiple tweets by U.S. President Donald Trump that indicated growing tensions between the two countries. The VanEck Vectors Russia ETF /zigman2/quotes/200464876/composite RSX -1.56% lost 3.1% in premarket trading, moving on volume of about 255,000 shares. Trump tweeted that the U.S. relationship was Russia " is worse now than it has ever been , and that includes the Cold War." The comment followed a suspected chemical-weapons attack in Syria. On Monday, Trump tweeted that Russia and its president, Vladimir Putin, were responsible for backing Syrian President Bashar al-Assad, and said there would be a "big price...to pay." Also on Wednesday, Trump tweeted " Russia vows to shoot down any and all missiles fired at Syria . Get ready Russia, because they will be coming, nice and new and 'smart!'" The U.S. dollar jumped 2.3% against the Russian Ruble /zigman2/quotes/210561862/realtime/sampled USDRUB +0.1845% and traded at its highest level against the currency since November 2016. The Russia ETF has been under heavy pressure of late, falling more than 11% thus far this week, not including Wednesday's premarket decline. Another Russia ETF, the iShares MSCI Russia ETF /zigman2/quotes/206979425/composite ERUS -2.36% has lost 9% thus far this week. Futures for the Dow Jones Industrial Average fell 1% on Wednesday while futures for the S&P 500 were down 1% and Nasdaq-100 futures lost 1%.