John McCain is a diplomatic disaster just begging to happen. A more generous observer than I might excuse his frequent factual gaffes - repeated references to countries and borders that don't exist, forgetting that Sunni al-Qaeda and Shiite Iran are sworn enemies, putting events such as Iraq's "Anbar Awakening" and the US military "surge" in the wrong chronological order - as the normal mental slippage anyone might experience while they near their twilight years. What cannot be so easily overlooked are those comments and actions of McCain's which suggest that he really is a rather angry and hateful old man, not to mention something of a loose cannon on the deck.

Take for example his efforts at humor involving the fantasized slaughter of Iranian civilians: His singing of "bomb, bomb Iran" to the tune of the Beach Boys' "Barbara Ann" back during the primaries and his more recent suggestion that exporting cigarettes to the Iranians might be a good way of killing them, neither of which should be coming out of the mouth of a prospective president. Following the "bomb, bomb Iran" incident McCain's lack of tact was made even more painfully obvious when he callously refused to admit any error in offending the Iranian people by suggesting that they would be better off dead. Whatever we might think of Iran's rulers, the Iranian people are not our enemies, and making jokes about killing them with bombs and cigarettes is no way to win "hearts and minds" in the Middle East or anywhere else.

McCain's remarks about killing Iranians echo previous comments made by him regarding the people of Vietnam. "I hate the gooks," McCain told reporters during his 2000 primary campaign, "I will hate them as long as I live." However rooted these comments may be in McCain's own war experiences, and however excusable they may be for any private citizen likewise scarred by war, they simply cannot be overlooked in a prospective president: the stakes are too high, the need too critical for a competent Diplomat-in-Chief in the Oval Office. Taken in the context of his later remarks about killing Iranians, they would also seem to suggest a fairly callous and cold-blooded attitude on McCain's part toward peoples he regards as enemies. Made once - and on the basis of such deep-seated hostility as that McCain appears to harbor toward certain peoples of the earth - such remarks may all too easily be made again, and again, and again.

Then we have the matter of McCain's infamous temper, such as when he reacted to disagreement on immigration reform from fellow Republican senator John Cornyn of Texas by screaming, "F*ck you!"; such as when he called fellow Republican senator Pete Domenici of New Mexico an "a**hole"; and such as when he called fellow Republican senator Charles Grassley of Iowa a "f*cking jerk." Keep in mind that these incidents occured, not in private or among political enemies, but on the floor of the United States Senate among fellow Republicans; and could therefore just as easily happen, say, at a G-8 Summit or a gathering of NATO leaders. How would it look on the world stage for a red-faced, whited-haired John McCain first to get all the countries wrong, then to make jokes about bombing one of them, then finally to blow his stack and call one of their presidents a "f*cking jerk"?

Indeed McCain's outbursts and insults have already, on occasion, occured before the eyes not only of America but of the world. His hatred of "gooks" and his desire to kill Iranians have both been widely noted in the world press, and would likely precede him on any presidential tour of Asia or the Middle East. While our French allies were fighting alongside US troops in Afghanistan, McCain had the following to say: "You know, the French remind me a little bit of an aging actress of the 1940s who is still trying to dine out on her looks but doesn't have the face for it" - not only insulting, but irrelevant, and quite possibly a reason for pro-American French president Nicholas Sarkozy's enthusiastic endorsement of Barack Obama. Once in a 1987 meeting at the height of Central American tensions, according to fellow Republican senator Thad Cochran of Mississippi, McCain reached across the table and physically assaulted a Nicaraguan representative, seizing him by his shirt collar. "The thought of his being president sends a cold chill down my spine...," Cochran later said when endorsing Mitt Romney for the 2008 Republican presidential nomination, "...He is erratic. He is hotheaded. He loses his temper and he worries me."

If McCain worries even his fellow Republicans, then how worried should the rest of us be?