Sanctions against Iran could have a negative impact on other countries, including Japan, which imports oil from Iran.

Japan should carefully and thoroughly study the impact of the new U.S. sanctions on Iran, which were recently approved by Congress.

The sanctions, which were included in an annual U.S. defense authorization bill, limit dollar-based transactions between U.S. financial institutions and those in foreign countries, including Japan, which engage in transactions with the Central Bank of Iran. The sanctions will come into effect six months after U.S. President Barack Obama signs the bill into law.

However, if Iranian oil supplies decline due to the U.S. sanctions, international oil prices are likely to jump. The sanctions will be meaningless if the oil price increase benefits Iran or cools down the world economy.

What is more disconcerting is the influence sanctions could have on Japan, which is Iran's second-largest oil export partner after China. About 10 percent of Japan's total oil imports come from Iran. Among U.S. allies, the sanctions are likely to affect Japan the most.

If sanctions are imposed, Japan could be doubly hit by difficulty in procuring oil and high oil prices. This would hinder rebuilding the nation from the aftermath of the March 11 disaster. Japan economy also may slow down.

According to reports, some exemptions are permitted, such as removing foreign financial institutions from the sanctions list if they meet certain conditions. The U.S. president also is authorized to refrain from imposing sanctions for security reasons.

The Japan g’sovernment must closely liaise with the U.S. administration and draw up measures to avoid Japan's oil imports being affected by the U.S. sanctions.

Other countries share similar concerns, such as South Korea--which imports about 10 percent of its oil imports from Iran--Greece, Italy, Spain and other European countries. 

We also need to keep an eye on Beijing's moves in relation to the U.S. sanctions, as China is the largest importer of Iranian oil. China has been critical of imposing any sanctions on Iran. If the U.S.-China relationship becomes strained because of the new sanctions, it will become more difficult to form an international coalition against Iran.