KENNEDY HOPEFUL SOVIET WON'T PUSH HARD FOR SUMMIT; Tells Khrushchev He'll Join Arms Parley If Early Talks Show Real Progress LETTER CALM BUT FIRM President, in News Session, Asserts Recent Easing of Tension Is Superficial KENNEDY ASSURES SOVIET ON SUMMIT
opposes opening conf on heads-of-govt level But does not rule out attendance later if progress warrants, reply to Khrushchev proposal for summit-level opening