The European Union yesterday imposed an embargo on future oil imports from Iran in an unprecedented escalation of sanctions aimed at forcing Tehran into negotiations on its uranium enrichment program. Foreign ministers from the EU’s 27 member states agreed to ban new purchases of Iranian oil and phase out oil imports under old contracts by July 1. The oil sanctions will be phased in gradually and reviewed on May 1 to cushion the impact on Greece, Italy and Spain, which face severe economic problems and depend more heavily on Iranian oil exports.

The new sanctions represent a significant escalation of international pressure on Iran. Many European nations long have given Tehran the benefit of the doubt and pursued a business-as-usual policy regarding Iran. But Tehran’s stubborn defiance on the nuclear issue, human rights violations, internal repression, and support for terrorism has gradually pushed Europeans toward a greater willingness to confront Iran’s thuggish regime. The EU also was moved to action by the International Atomic Energy Agency’s November report on Iran’s nuclear weapons efforts and the regime’s orchestrated attack on the British embassy compound in Tehran later that month.

Iran exports about 2.2 million barrels of oil per day, of which about 18 percent is consumed by the EU, Iran’s second-biggest customer after China. Most of Iran’s oil exports are slated for Asia, with about 20 percent going to China, 17 percent to Japan, 16 percent to India, and 9 percent to South Korea. South Korea and Japan are expected to reduce their imports of Iranian oil in the future, adding to the weight of previous sanctions, while China and India are likely to drag their feet on western requests to impose more sanctions on Iran.

Iran’s Foreign Ministry reacted strongly to the new EU sanctions, saying that they were “unfair” and “doomed to fail.” A senior member of Iran’s sham parliament warned that Iran would “definitely” close the Strait of Hormuz if the EU embargo disrupted its oil exports.

But Tehran is unlikely to follow through on its threats as long as its oil exports, which need to pass through the strait, continue to be purchased by Asian customers. To underscore their commitment to safeguarding the free passage of shipping through the strait, the United States, Britain, and France deployed warships that passed through the strait yesterday into the Persian Gulf.

Escalating sanctions can only do so much to pressure Iran to comply with its treaty obligations on nuclear non-proliferation. But military power, in the form of a strong naval presence, is necessary to deter Tehran from turning its bellicose threats into actions that would undermine a vital U.S. interest in assuring the free flow of oil out of the Persian Gulf. A disruption of the flow of oil could cause a worldwide oil price spike, which would harm not only America’s economy but also the global economy.