Willems was installed as Minister of Defense sometime in the 11 days between Dur Gejjen's rise to the position of Five World Prime Minister and Admiral Wedge Antilles' meeting with Han and Leia Solo aboard the Thrackan Sal-Solo in the Kiris Asteroid Cluster. When Antilles and Gejjen asked the Solos to meet with Hapan Queen Mother Tenel Ka Djo, it was revealed that Willems was to go in their place if they refused.
Willems helped convince the Solos to go on this diplomatic mission, partly through his heated exchange of words with Han and partly by simply being present to see the what a poor replacement he would be if they refused.