Balk or not????

[slowballbaker]

Need help on this one...

Runner at 1st base..
Pitcher is in the stretch...Right handed pitcher..
Pitcher gets the sign and then comes set....
Pitcher then leans back and steps "backwards" towards 1st
base with the left foot..(shoulders still facing 3rd base)..
Then when the left foot lands pitcher turns and throws to 1st base trying to pick the runner off...
Balk???
No Balk??
Why or why not???/

Thanks....