Pat Lang has more background:
...The tensions between the Turkish government and dissident Kurds is what it has always been. Sporadic fighting and terrorist action in Turkey is a continuing fact of life in the region. The Turkish government regards northern Iraq, with some justification, as a sanctuary and redoubt area for Turkey's Kurdish rebels.
The United States has encouraged the ambitions of Kurdish Iraqis for political and social autonomy in the north. The US has protected a nearly independent Kurdish autonomous zone for over a decade. It should be obvious that the real aspiration of the Kurds is northern Iraq is independence.
Turkey regards that as a threat to its long term stability and territorial integrity.
Should the American government not have foreseen that? How difficult was it to see that coming? Has the US government tried hard to resolve the potential for further war in the region over this issue?Now Turkey is assembling its forces on the border. It is not too late to act. The US government shold aggressively seek an agreement in which Turkey and the Kurdish entity in the north accept a US guarantee (enabled by an American military presence) that preserves both Kurdish and Turkish equities. The US is now a Middle Eastern regional power and must accept its responsibilities as such.