Daiwa Securities Group President Yoshinari Hara has warned investors not to be optimistic about the U.S.-led military action against Afghanistan's ruling Taliban regime, noting prolonged conflict could seriously impact the world economy.

Hara said he hopes the action against the Taliban and Osama bin Laden, the prime suspect behind the Sept. 11 terrorist attacks on the World Trade Center and Pentagon, will end quickly.

"After the attacks, the world's top concern has been how the stock market would react. Stock markets are the heart of the world economy," Hara said.