What happens if I cross the ADIZ line without a flight plan and no clearance or contact with ATC? I'm on a flight to/from the Caribbean on a single engine Cessna and I crossed the ADIZ (Air Defense Identification Zone) line.  I haven't filed a flight plan, I don't have clearance from ATC, and I'm not in contact with ATC.  I do have mode c transponder active on ALT and code is 1200 (VFR) and my altitude 6500 ft MSL.  

The ATC would see the aircraft, its altitude, and its velocity.  Based on this flight data, ATC would most likely conclude this was an ignorant or lost pilot or lost drone, and no threat posed.  Have there been any instances where military or coast guard air craft were actually sent for  interception of such small and slow aircraft?  What are the statistics on this?  What would the fines and penalties be?  I'm assuming this would apply more when entering the US ADIZ than exiting.
In the late 60's, in a C152. I flew a guy, at a low altitude out of Key West to the Marquessa Islands area to look for sunken Spanish galleons.  On the return trip I was nervous flying at 200 feet above the ocean and climbed up to 3,000 feet.  After a few minutes al said altitude my windscreen flashed black. A F-4 had come from behind and below - zoomed up a few yards in front of me! Looking behind me I saw his wingman, gear and flaps down, S_turning on my six.

A quick call to FSS clarified the situation.

That is what happened to me upon inadvertent entry into the ADIZ. I don't expect it has changed.  There were no followup actions other than the echos of the F-4's pilots laughter.