The goal of this post is not in any way defending Turkey (disclaimer: I am a Turkish citizen) but attempting to make international audience understand how Turkey as a state and Turkish public see things and react accordingly. Before we come to the current incursion let's have some history and maps.

Our first map is from the Treaty of Sèvres which was signed between Ottoman Empire and the Allies after the World War 1:

Sèvres Map
(my img tags are being stripped so you have to do with links.)

As you can see the area is give or take 1/4th of current Turkey and most of the strategic points and fertile land is taken away. This prompted the Turkish War of Independence and at the end of it, Treaty of Lausanne gave Turkey her current borders.

One can say that Turkey still lives with Sèvres paranoia and fears losing parts of her lands. This may sound unrealistic and I also believe that won't happen given Turkey's current international position and strength. It is also a fact that this card is played against Turkey in many situations by different actors and make things more complicated everytime.

In the '60s and '70s there was the Cyprus problem for instance. Greek Cypriots supported by the military government in Greece were openly on a way for Enosis, uniting the island with the mainland. Of course, Cyprus was not part of Turkey but it constantly reminded the panhellenic aspirations of our neighbours which claim right to Constantinople (Istanbul) and Symrna (Izmir) as well. Even the largest center-left party was called Panhellenic Socialist Movement so you may cut some slack to Turks for assuming these aspirations were mainstream and may be they were mainstream those days I don't know.

During the late '70s and early '80s, ASALA was killing Turkish diplomats and demanding territory for an Armenian homeland based on the Sèvres map. Then came the PKK fighting for independence. As you can see, for the most part of the last 3 decades Turkey fought problems which are this or that way related to losing parts of its territory.

In June 2006, an article was published in Armed Forces Journal including a map of new Middle East where South Eastern Turkey and part of Eastern Turkey was given to Kurdistan. Turkey originated IPs are blocked after this caused an angry reaction in Turkey but I believe the article is here, before map is here, and after map is here. After assurances from American civil and military officials this was only opinions of the author, the same map resurfaced in a NATO briefing later in Rome causing another storm:

Lieutenant-Colonel Ralph Peters’ map of the “New Middle East” has sparked angry reactions in Turkey. According to Turkish press releases on September 15, 2006 the map of the “New Middle East” was displayed in NATO’s Military College in Rome, Italy. It was additionally reported that Turkish officers were immediately outraged by the presentation of a portioned and segmented Turkey. The map received some form of approval from the U.S. National War Academy before it was unveiled in front of NATO officers in Rome. The Turkish Chief of Staff, General Buyukanit, contacted the U.S. Chairman of the Joint Chiefs of Staff, General Peter Pace, and protested the event and the exhibition of the redrawn map of the Middle East, Afghanistan, and Pakistan.
source

Recently, The Atlantic Monthly's 2008 Jan-Feb had an article by Jeffrey Goldberg involving a similar map which found some coverage in the Turkish media. The map was also used as the cover of that issue.

When one looks at these kinds of maps, it generally generates some intellectual neuron firings only but when you see your country partitioned, realizing some important people are talking about this, even it is a slight probability it may happen and the city you were born and raised or just visited and enjoyed may belong to another country in the future, it generates other feelings as well.

On top of all this history, as the Pew polls show Turkish public grew very suspicious about the West in the last 5 years. The Iraq war, the Greater Middle East talk, EU's demands for membership, passing of Armenian Genocide bills at congresses all contributed to this. Turkish public also never forgot the events before PKK's founder and president Abdullah Öcalan – bin Laden of Turkey – was captured. These were seen as hard evidences of Europe's support of PKK and its cause.

I wrote all these to say that Iraq war was mainly seen in Turkey from the point of Northern Iraq, namely how an independent Kurd state there will affect Turkey. Some fear that this may increase independence aspirations among Turkish Kurds. Some say that even that won't be the case such a pawn state will be used to make Turkey deal with PKK or similar groups for a long long time.

Although Turkey is realizing this may happen eventually, even it may be unavoidable, it won't let it happen without a fight. But it seems like, at least for the moment, that fight won't be fought by the military. There is a growing consensus about using Turkey's international position and economic power as the main tools to oppose or delay such a future. Of course, the high road to take is let Iraqis decide their future and concentrate on problems at home related to the Kurds but these are minority opinions for now.

As for the recent incursion, I believe it will be limited, short termed and focused on only PKK. This surprized the Turkish public as well, since air strikes were thought to be sufficient at the moment and demand of the public for a land operation diminished after we moved on to our other hot button issue (headscarves and laicism). When land operation was being discussed, many people pointed to the dangers of such an operation (i.e. confrontation with the peshmargas, civilian casualties) and the perception was that government and military dismissed the idea as well.

It now seems like with the help of US intelligence those strikes were pretty efficient and military decided to follow up on it to give more damage and make harder for PKK gaining strength in the spring as it did previous years. PKK violence is cyclic and these kind of operations were held before proving to be pretty effective to quell the violence. Nobody expects the problem will be solved by only military means (Turkish military says so for a long time and demands politicians to be more active) but it is also hard to deny the effect of such operations.

If we look at the bigger picture, although the incursion will be limited, analysts are saying that US approved, even encouraged this despite Kurdish leaders' objections to make them work more closely with the central government. There is no doubt this fits well with Turkey's objective of discouraging Kurdish autonamy.

So I suggest not getting very excited about this incursion. Starting with PM Erdoğan's visit to G.W. Bush last September, there have been very high level contacts between Turkish and American military. This shows that Turkey won't do anything that will be unacceptable for US mission there. Regional Kurdish leader Barzani also toned down its rhetoric a lot and won't use his pesmharga to escalate the situation. In the past operations, there were cases where Talabani and Barzani supported Turkish troops and fought PKK. There are state allied Kurdish tribes in Turkey fighting the PKK as official militias. At one point, I read somewhere but didn't verify afterwards, Barzani (or Talabani) allied with Saddam to capture back a city from his opponent. What I am trying to say is these things are more complicated than the Western media portrays. I just hope that both Turkish army and PKK have minimal casualties and this operation won't hurt any civilians and damage Kurdish infrastructure. Other than that I am not too worried.