The U.S. dollar remained firm above the 161 yen line, briefly trading in the mid-161 yen zone in Tokyo on Friday, with the currency market showing little reaction to Finance Minister Satsuki Katayama's warning of "decisive" action if speculative moves weaken the Japanese currency.At 5 p.m., the dollar fetched 161.31-33 yen compared with 161.32-42 yen in New York and 160.59-60 yen in Tokyo at 5 p.m. Thursday.The euro was quoted at $1.1446-1447 and 184.64-68 yen against $1.1452-1462 and 184.90-185.00 yen in New York and $1.1512-1514 and 184.88-92 yen in Tokyo late Thursday afternoon.The yield…READ FULL ARTICLE