President Obama issued an executive order Tuesday tightening sanctions on Iran and Syria by prohibiting financial transactions with foreigners who have evaded existing sanctions with those countries and denying them entry into the United States.

The order targets foreign residents and businesses that have violated or attempted to violate U.S. sanctions against Iran or Syria.

Under the order, the Treasury Department, with help from the State Department, has the capability to publicly identify the violators and essentially bar them from U.S. financial and commercial markets.

“Whoever tries to evade our sanctions does so at the expense of the people of Syria and Iran, and they will be held accountable,” said David Cohen, under secretary for Terrorism and Financial Intelligence.

The White House said the executive order is the latest in a series of steps taken by the U.S. and international partners targeting the governments of Iran and Syria with respect to their abuse of human rights, support for terrorism and the proliferation and development of weapons of mass destruction.

The administration last week issued an order that suspended the entry into the country of people connected to the Iranian and Syrian government committing human rights abuses through the disruption of computer networks as well as using computers to monitor or track residents.

The U.S. has already frozen the property and interests in property of the government of Iran, its agencies and all of the country's financial institutions, including the Central Bank of Iran. The Treasury Department has identified more than 400 such people or entities.