Closer to conflict between the Turks and Kurds

This morning the Turkish government announced it would be launching several large scale offensives against "Kurdish rebels" in southeastern Turkey, now we have this,

Turkey's military asked the government Thursday to approve attacks on Kurdish rebels in northern Iraq, signaling growing frustration over a lack of action against the guerrillas by Iraqi and U.S. forces.

Again, I don't think we're at the point of no return, but the situation has reached a point where it could rapidly escalate if something triggers an open conflict.

If something does open up, what does the US do? Go to war with Turkey? Try to attack only the PKK? (You and what army?) Sit idly by?

(It should be noted that Turkish elections take place in May, so that may be affecting both this statement and any response by Erdogan. Turkey's military plays a huge role in their domestic politics.) Other versions: AFP, BBC.