Asked recently whether the U.S. plans to attack Iran, chairman of the Joint Chiefs of Staff Admiral Mike Mullen said, "I think the military options have been on the table and remain on the table." On the face of it this implies the U.S. is contemplating an attack on Iran.

But was his comment an indication of U.S. intentions, or was he just trying to improve America's bargaining power by using threatening language?

The U.S. has been equivocal about a military strike on Iran for years. And the timing of Mullen's comment is significant. After the United Nations approved a new round of sanctions on Iran in June, the U.S. imposed further unilateral sanctions. And the European Union, the old ally of the U.S., followed suit with tough new sanctions on Iran's energy sector, including oil and gas, the backbone of Iran's economy.

But Iran has become accustomed to western sanctions and so far has shown no signs of giving in.

The U.S. Secretary of State and the Secretary of Finance have both said that the U.S. government remains committed to solving the Iran nuclear issue through diplomacy. And a Pentagon spokesman said that the U.S. is planning talks with Russia, China, France and Germany on the issue, adding that such talks are appropriate channels of communication.

Iran has also submitted a letter to the International Atomic Energy Agency (IAEA), calling for a resumption of nuclear talks. The letter expressed Iran's readiness to start talks on a uranium swap deal.

Mullen's comment on a possible strike against Iran is best explained by the old Chinese saying, "There can never be too much deception in war." The discord between the U.S. and Iran has lasted decades. Sometimes they cross swords verbally and sometimes they threaten each other with the use of force. But they have never taken things to the brink.

The U.S. is already mired in two wars, in Afghanistan and Iraq. It is also occupied holding military drills with South Korea and meddling in the South China Sea.

The U.S., despite claiming to be the "world's policeman", is not likely to start a war with Iran at this time. Mullen's comment should be seen as a "stress test" on Iran conducted by the U.S. military.

(The article was first published in Chinese and translated by Zhang Ming'ai)