The United States has been forcing other countries to comply with the United Nations sanctions against Iran, and it has been blaming Chinese companies for breaking the embargoes on Iran.

China has been facing a dilemma over the sanctions imposed on Iran. On one hand, China has important business and strategic interests with Iran. On the other, as a permanent member of the UN Security Council, it has to act as a responsible power to maintain world peace and security.

It is clear that China's relations with Iran do not depend only on the two countries. They are determined by China-US and China-European Union (EU) relations as well. Thus Sino-Iranian relations pose a great challenge to China's diplomacy - a tricky diplomatic battle which, if not handled properly, could harm China's core interests.

Since China replaced the EU as the largest trading partner of Iran last year, it is likely that Iran will become the biggest foreign construction and project market for Chinese companies. As the second largest oil producer among the Organization of Petroleum Exporting Countries and the fourth largest oil exporting country in the world, Iran is also China's third largest source of petroleum, accounting for 11 percent of its total imports.

Moreover, since Iran has rich and inexpensive oil and gas resources that are of great importance to China, Beijing has to maintain friendly cooperation with Teheran to minimize its energy security worries.

Therefore, China was reluctant to impose new sanctions on Iran, even though the West had been demanding them ever since Teheran announced on Feb 8 that it would enrich its on-hand uranium to 20 percent.

After assuming office, US President Barack Obama tried to seek a dialogue with Iran, but his year-long diplomatic efforts were in vain. That prompted Obama to hold the Nuclear Security Summit in Washington on April 12. In such circumstances, any disagreement between China and the US would run counter to the aim of establishing full-scale cooperative Sino-US partnership and taking joint steps to confront global challenges.

Now that China, according to media reports, has become the world's second largest economy, it is impossible to solve a global problem without China's participation. But as a permanent member of the UN Security Council with veto power, China is not expected to fight only for its own interests. Its actions should be aimed at maintaining a stable international security order.