In legal-speak, he would have to say “I believe.” If he said definitely “yes” he would have to present evidence, which he cannot.
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He cannot present evidence because the evidence is classified, and to reveal any of it, or even present the appearance of certainty, would identify him and be his death warrant.
“He cannot present evidence because the evidence is classified, and to reveal any of it, or even present the appearance of certainty, would identify him and be his death warrant.”
Yes. That was my assumption.