"We are now facing an existential threat to the security of the United States of America," said McCain.
But nothing that happens in Mesopotamia is going to threaten the existence of the United States. As for the terrorist threat from ISIS, for us it is neither greater nor less than it was a week ago.
The existential threat here is to Iraq. Its survival as one nation is now in question, with the possibility it could be torn apart in a civil and sectarian war. But this is preeminently Iraq's problem, not ours.
And if Prime Minister Nouri al-Maliki, his 900,000-man army, and Shia militia cannot defend Baghdad from a few thousand Islamist warriors, America is under no obligation to do it for them.
Maliki told us to go home three years ago. We did. And before we plunge back into that misbegotten war, let us consider what the real threats are -- to America.
The Islamic State of Iraq and Syria consists of fanatics who seek to carve a caliphate out of territory they now control from Aleppo in Syria to 60 miles north of Baghdad.
Yet they have halted before Baghdad. And among the reasons is that Iraq's Shia majority is not going to allow Sunni zealots to capture their cities, smash their shrines, and murder their fellow Shia.
They will fight, as the Iraqi army did not.
Secondly, ISIS has as allies in the north and west of Iraq Sunnis who detest Maliki and wish to be rid of him. But these Sunni are not demanding a Taliban regime to abolish smoking and drinking. Nor are they fighting to cut off the heads of their Shia countrymen.
If ISIS goes beyond the liberation of the Sunni triangle to trying to take over all of Iraq, they will lose many Sunni allies and find themselves facing Iraq's Shia majority, backed up by Iranian forces, virtually alone.
But while the Iraqi army and Shia militia may well hold Baghdad, it is hard to see how Maliki can soon reconquer the Sunni provinces. For the Sunnis want no part of him or his regime.
Nor does Maliki seem capable of taking back Kirkuk, which the Kurds seized in the chaos as a step toward independence.
What should America do? Take a hard look at our entire Middle East policy.
Consider. We are now providing weapons to the Free Syrian Army to oust Bashar Assad. "Assad must go!" blared Barack Obama in one of his many ignored ultimata.
But should Assad fall, the result will be the persecution of the Syrian Christians, a massacre of the Alawites, and a possible takeover of the country by the al-Qaida-linked al-Nusra Front and ISIS.
Is any of that in America's interests?
Vladimir Putin lately raised a valid question: Why, in Syria, are the Americans on the same side as the people who took down the twin towers? Indeed, why are we?
And who is fighting al-Qaida and ISIS in Syria, battling those McCain calls an "existential threat" to American security?
Bashar Assad. Hezbollah. Iran. Russia.
Tehran has reportedly volunteered to work with us in providing military aid to prop up the Maliki regime and keep ISIS out of Baghdad.
If we regard the survival of the Maliki regime to be in our national interests, why would we not green-light the Iranians to do this?
When Hitler turned on his partner Stalin, the United States rushed military aid to save the monster whom FDR and Truman took to calling "Good Old Joe" and "Uncle Joe" at Tehran, Yalta and Potsdam.
Is the Ayatollah somehow worse than Stalin?
Yet, consider, too, how our allies in the Gulf and Middle East have behaved in Syria.
The Turks, clamoring for the overthrow of Assad, looked the other way as jihadists moved into Syria. The Gulf states and Saudis have reportedly sent money and military aid to the extremists.
Are the Turks and Gulf Arabs aiding these jihadists in the belief they will not turn on them, if and when Assad and Maliki fall? Do they think that by feeding this tiger ISIS, it will eat them last?
We may be entering the early stages of a sectarian war between Sunni and Shia across the Middle East. The ISIS claim of having executed 1,700 captured Shia soldiers in Iraq is surely intended to ignite one.
If it happens, this war could spread to Lebanon, Jordan and down into the Gulf states where Shia outnumber Sunnis in Bahrain and in the oil-producing provinces of the Saudi northeast.
Does the Middle East today -- Iraq, Syria, Yemen, Libya, Lebanon -- look like what we were promised by George Bush and his neocon advisers when they were beating the drums for a U.S. invasion of Iraq?