itachi??....or madara?...n what kind of contract?Maybe since he has the MS like Madara but it looks like he also had a contract with the 9 tails since he was trying to summon it.
this takes the cakeItachi cannot cut off naruto's KM mode chakra supply because it is only chakra and dosen't have a mind.
However , all sharingan users can subjecdicate the nine tails , though with varying degrees. the stronger the eye( 1 tomoe ->2 tomoe -> 3 Tomoe , Ms , EMS) , the more you can subjectdicat ethe kyubi