Donald Trump is nothing if not unpredictable as president. But when it comes to foreign policy, that just might be his greatest foreign policy asset. After all, America's ability to swing between aloofness and overreaction are embedded in its DNA thanks to its inherently strong geopolitical foundation. A mercurial spirit in the White House might make some big waves, but can also — at least in some circumstances — be harnessed into an opportunity. A grand strategist like Dr. Henry Kissinger, who has been known to advise Trump on occasion, likely detects such an opportunity in a Trump presidency. Kissinger, now 95 but lucid as ever, has made himself available to several presidents and candidates to help shape foreign policy and engage in quiet shuttle diplomacy.