The U.S. Treasury Department has proposed cutting off a Swiss bank from the U.S. financial system due to alleged illicit ties with Iran and Russia. This move, described as a dramatic step, could trigger severe sanctions against the bank, disrupting its access to critical financial services. The action underscores growing U.S. pressure on institutions facilitating transactions for sanctioned countries. Markets may react with increased volatility as geopolitical tensions and financial system fragmentation concerns rise.