What does claudius ask rosenchants and gildenstene to do in act 4 hamlet?

In Act 4, Scene 3 of Hamlet, Claudius asks Rosencrantz and Guildenstern to accompany Hamlet to England.

He instructs them to take a letter with them, which is actually a sealed warrant to have Hamlet executed. Claudius assures them that it is for Hamlet's own good and that he will be safe under their care. However, his real intention is to eliminate Hamlet as a threat to his rule.