Factbox - U.S. Congress considers further Iranian penalties

WASHINGTON (Reuters) - Iran's trading partners are scrambling to comply with the latest U.S. sanctions against Iran. If countries such as China, India and South Korea do not cut down on their Iranian oil imports by mid-year when the U.S. sanctions go into effect, their financial institutions could be blocked from U.S. markets.

But U.S. lawmakers are considering additional legislation that would