Based on a July 25 editorial, ". . . And a Captive Treaty," The Post's readers may have the impression that during my May 26 testimony before the Senate Foreign Relations Committee, I endorsed the Comprehensive Test Ban Treaty (CTBT). When I was asked about the treaty, I endorsed, as The Post's editorial correctly pointed out, its possible utility in inhibiting nuclear proliferation. But I withheld my final opinion because I was not prepared to discuss all its nuances at a hearing that was on a different subject.

When I was involved in test-ban negotiations, it was understood that testing below a certain threshold was required to ensure confidence in U.S. nuclear weapons. It also was accepted that very low-yield tests would be difficult to detect, and an agreement to ban them would raise serious questions about its verifiability. The CTBT is a "zero yield" treaty. This makes the CTBT a different agreement from the one I was involved in negotiating. As a result I told members of the Foreign Relations Committee that I was not prepared to provide them with an analysis of the CTBT until I updated my knowledge on the testing issue.

HENRY KISSINGER

New York