According to this article:

Turkey is demanding that it send 60,000 to 80,000 of its own troops into northern Iraq to establish "strategic positions" across a "security arc" as much as 140 to 170 miles deep in Iraq. That would take Turkish troops almost halfway to Baghdad...

independent diplomatic sources in Ankara and Washington with knowledge of the US-Turkey talks say that while the precise depth of the "security zone" has still to be agreed, the concept is "pretty much a done deal," as one observer put it...

"Turkey is playing hardball," said Michael Amitay of the Washington Kurdish Institute. "But if the US agrees to these Turkish deployments, there is a real risk that the Kurds will start a guerrilla war against the Turkish troops."