Our missile technology is good (maybe not top-rated yet, but no one in the world is going to sell you Agni range of missiles just like that). We can indegenously develop missiles to strike all our enemies and that is because of kalam.
DRDO had failed in its initial attempts at developing guided missiles and then they brought in kalam. He made it a success. What people fail to understand is he is not a 'scientist' in the popular sense, he is a technology manager, and he used his experience to form a team that could achieve the goal.... That in a place like DRDO. That is his achievement.