How much of a threat is Hamlet to Claudius?

At this point in Hamlet, everything is getting real intense and hectic. From hamlets "love" for ophelia and his insanity, to the foreign affairs happening outside of elsinore. Both Hamlet's insanity and foreign affairs come up here at the same time. THis is where the argument that Hamlet is a large threat to Claudius. As we see in 2:2, the subject of foreign affairs comes up, and what does Claudius do? He merely brushes it away, and moves on to his concern about Hamlets sanity. Claudius is a selfish man, and shows that his concern is more with his own self rather than the safety and protection of his people. Hamlet poses a huge threat to claudius, and he seems willing to do anything to figure out what is going on with Hamlet, so that nothing happens to him. Whats the threat tho? Im not too sure, but maybe he thinks that Hamlet knows about his murder, ands is afraid of what the outcome of that may be. Maybe its the threat of Hamlet taking over the throne. Or maybe, since Hamlet is like this, he is afraid that Hamlet may take Gertrude from him.

Lets hope thats not the case. . .