This document proposes an interbank blockchain platform to help banks better detect money laundering and counter terrorism financing. The platform would allow banks to share non-sensitive transaction data in real time. A backend rule engine and later analytics platform would use this pooled interbank data to form risk scenarios, detect complicated placement and structuring techniques, and reduce false positives and compliance costs compared to individual bank systems. Simple example scenarios show how the shared ledger and analytics could help identify suspicious loan repayments or transfers below individual bank detection thresholds that together may indicate placement efforts.