"History is littered with the wars which everybody knew would never happen." - Enoch Powell, British Politician (1967)

This week, the Turkish parliament gave the central government the go-ahead to undertake cross-border operations into Iraq against the Kurdish terrorist-separatist group, the Kurdistan Worker's Party (PKK.)

The good news is that Turkish Prime Minister Recep Tayyip Erdogan insists an attack isn't imminent. The bad news is that a large-scale incursion could have serious consequences for U.S. interests in Iraq.

It's no surprise the Turks are up in arms. PKK forces based in Iraq have recently attacked both civilian and military targets in Turkey. PKK rebels reportedly killed at least 15 Turkish soldiers and a busload of civilians in the last two weeks.

The ruling Justice and Development Party (AKP) is under tremendous domestic pressure to do something about the PKK, which may be responsible for at least 100 soldiers deaths this year alone.

Indeed, the PKK is responsible for 600 total deaths last year. Since 1984, when the PKK began its armed push for an independent Kurdish homeland in southeastern Turkey, over 30,000 have died.

And a Turkish incursion into Iraq against the PKK wouldn't be unprecedented. Turkish forces have crossed the border a number of times, sometimes in large numbers, in pursuit of the PKK since the conflict broke out.

Just this June, Turkey massed ground forces along the Iraqi border, without the green-light it now has from the parliament, after a spate of PKK killings in Turkey.

For the moment, though, Turkey probably isn't going to invade. But in the meantime, the saber rattling serves other purposes.

First, the authorization for the use of force sends a nasty shot across the bow of both Baghdad and Washington (a NATO ally) to do something substantive about the PKK, operating out of Iraq.

Ankara understands the last thing Washington or Baghdad wants - or needs, especially when things seem to be going better in Iraq - is a problem like Turkish forces pouring across the border.

While U.S. and Iraqi leaders have been cautious about saying what they might do if Turkey invades, Turkish forces (NATO's second largest) could unintentionally attack U.S. troops - or meet fierce resistance from local Kurds or the Iraqi army.

Such ugly possibilities are a real incentive for the United States and Iraq to do something. Ankara, is demanding meaningful action and progress on eliminating the PKK in Iraq , not just more promises. (Turkey and Iraq recently signed a counterterror cooperation pact.)

In addition, the Turks were furious that our House of Representatives planned to take up a nonbinding resolution on the massacre of Armenians in the Ottoman Empire during World War I. Ankara has threatened to close Incirlik airbase to us - a threat that seems to have lead House leaders to back off. If Ankara does cut off access, the Pentagon can reroute the large volume of cargo and fuel bound for U.S. troops in Iraq - but the possibility of a large-scale military action ratchets up the pressure astronomically.

Of course, the Turkish threats could be all bluff and bluster, especially by a ruling party that is looking to boost its sagging public support with a little jingoism. Then again, why should we take a chance when so much is at stake?

Now, the PKK isn't just in Iraq. Ankara has a PKK problem on its side of the border, too. But Washington and Baghdad must do their best to close PKK camps in Iraq, eliminating the need for Turkish cross-border operations.

The United States and the Europeans could also help Turkey with the PKK through more robust intelligence collection and sharing. (Both the European Union and the U.S. State Department list the PKK as a terrorist organization.)

NATO generals can encourage restraint with the powerful Turkish military brass, too. And Brussels - while doing more itself to dismantle PKK networks in Europe - should remind Ankara of repercussions of military action on its long-held goal of joining the EU.

Hopefully, cooler heads will prevail. But considering Turkish politics, strained Ankara-Washington relations and the PKK's relentless terror campaign, a major Turkish incursion into Iraq could become a reality.

Peter Brookes is a Heritage Foundation senior fellow and former US deputy assistant secretary of defense.