"What I can't quite see at this stage is that the evidence, even to the president, seems to be that clear. And if it is that clear, I can't understand why we are not capable of convincing our closest allies that given that evidence, they ought to join us in this effort"

This quote by Lawrence Eagleburger recommends that the evidence provided to the president is clear, yet the president is not able to encourage their closest allies to join them in their effort. This could be due to a lack of trust between the allies, or a lack of understanding of the evidence provided. Eagleburger is implying that if the evidence is clear, then the president ought to have the ability to convince their allies to join them in their effort. This might be done by supplying more evidence, or by constructing a more powerful relationship with the allies. Eventually, Eagleburger is suggesting that if the proof is clear, then the president should have the ability to convince their allies to join them in their effort.