You acknowledge the move, optimistically. All the while being prepared for the worst case scenario. If you (anyone, not you specifically) believe that any agreement with any Arab country is going to result in the destruction of Israel, I can understand why people believe negotiations are useless. It would be foolish to believe such a statement and remove all army presence from the South of Israel and the West bank. I do not think it is foolish to acknowledge the statement and reciprocate positively. Not threatening to bomb Gaza, for example. Or threatening not to talk to the PA is Hamas is present.
At least 13 killed in bomb explosion suburb of Baghdad (Reuters)