A group of 16 Republican senators led by Ted Cruz of Texas have urged US Treasury Secretary Stephen Mnuchin to expel Iran from the main financial system that oversees international bank transfers. Their move on Thursday came as US President Donald Trump has been exerting strong pressure on Tehran after reimposing a wave of tough sanctions earlier this month targeting Iran’s trade in gold and other precious metals, its purchases of US dollars and its car industry. Other sanctions will come into force in November. “We urge you to take all necessary steps to ensure the Society for Worldwide Interbank Financial Telecommunication (SWIFT) disconnects the Central Bank of Iran (CBI) and all other designated Iranian financial institutions,” the senators wrote. "The administrations maximum pressure campaign will not succeed if Tehran “remains connected to SWIFT," they said. The senators stressed that “quick robust enforcement will be critical for the administrations maximum pressure strategy to succeed, both immediately to drain the Iranian regimes resources for malign behavior and as a signal of Americas commitment to maintaining the integrity of our sanctions architecture." The letter came a day after Trump’s national security adviser John Bolton said the US sanctions are having a strong effect on Iran’s economy.