Well, "under our laws" may be a non sequitur here, as I don't think any of the discussion, with one possible exception, has involved any law of the US.
Please acquaint yourself with the crimes under discussion. "The Trial of Henry Kissinger" is one source. There are many others.
As to other laws, most importantly the international body thereof, there is a respectable--note I do not say persuasive, as I don't have enough facts--that Kissinger as a "subordinate" was carrying out the policy of the state and, as such an actor, may be clothed with sovereign immunity.
Kissinger was hardly a flunky. As chair of the "40 Committee" from 1969-1976 Kissinger personally oversaw all U.S. covert actions. He had tremendous power in the Nixon and Ford administrations. ("Do not follow the President's orders without clearing them through me.") And, since when is being a flunky an excuse? We're all supposed to follow the laws. It's basic to our system of government that the executive branch and its employees are not above the law. The U.S. hanged a number of people at the end of World War II as "war criminals" who had less relative responsibility than Henry Kissinger. The U.S. supports international tribunals now. Therefore, under the stated beliefs of the U.S. government Kissinger should be subject to these sorts of proceedings. Concerns about international tribunals are valid. If you reject them for all leaders you may be making sense. But, it sounds as if you reject them only for Kissinger.