NEW YORK - US stocks have opened flat on Tuesday as markets looked ahead to President Barack Obama's State of the Union address in the evening. LONDON - European stock markets rose, with a G7 countries warning of foreign exchange volatility pushing up the yen, while dealers also digested news of job cuts across the banking, airlines and telecoms sectors. However, a warning by the Group of Seven top industrialised nations amid growing rumblings of a "currency war" sent the yen climbing. The euro stood at $1.3450 compared with $1.3404 late in New York on Monday. HONG KONG - Asian markets were mixed in holiday-thinned trade, with Tokyo boosted by a weaker yen, while Seoul was lower after news that North Korea had successfully tested a nuclear bomb. With several regional markets still closed for Lunar New Year celebrations, trading was quiet, while dealers look ahead to a meeting of the Group of 20 top economic power at the end of the week. Tokyo climbed 1.94 per cent, or 215.96 points, to 11,369.12, while Sydney closed flat, nudging down 0.5 points to 4,959.0 after peaking earlier in the day at a 34-month high. Seoul, which was already flat after the North Korea reports, was off 0.26 per cent, or 5.11 points, at 1,945.79. WELLINGTON - The NZX 50 Index fell 2.38 points, or 0.1 per cent, to 4218.12.