Hansen made his international debut with Denmark in Division I play of the 2002 IIHF World U18 Championships, held in Slovenia. At 16 years old, he was the second-youngest player on the under-18 team; he went pointless in four games. Denmark narrowly avoided relegation to Division II, beating out Japan on goal-differential by one. At the 2003 IIHF World U18 Championships, Denmark finished first in their Division I group, earning a promotion to the main tournament for the following year. In Hansen's second tournament appearance, he tied for sixth in Group A scoring with seven points over five games.