GDANSK: Former enemies and allies

sombrely marked the 70th anniversary of the start of World War II on Tuesday,

underlining the need to remember the bloodiest conflict in the 20th century.

Russian PM Vladimir Putin, whose country sided with Nazi Germany during the initial invasion of Poland in 1939, said the war and its causes needed to be studied from all perspectives.

Poland's leaders gathered at dawn on Gdansk's Westerplatte peninsula to mark the exact time the German battleship Schleswig-Holstein, in the war's opening salvo, shelled a tiny Polish military outpost housing the navy's arsenal.