TOKYO, March 7 (Xinhua) -- Tokyo stocks opened lower Wednesday as investors were cautious following choppy trade on Wall Street overnight, as concerns resurfaced about a trade war after Washington showed mixed signals about whether U.S. President Donald Trump would follow through with his tariff proposals.

As of 9:15 a.m., the 225-issue Nikkei Stock Average dropped 141.82 points, or 0.66 percent, from Tuesday to 21,275.94.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, dropped 7.92 points, or 0.46 percent, at 1,708.38.

Iron and steel, oil and coal product, and nonferrous metal-linked issues comprised those that declined the most in the opening minutes after the morning bell.