Japan needs to see its strategic security through a wider lens than the resource concerns of its powerful economic ministries. Japan's decision to fund the development of Iranian oil "against Washington's objections" ignores this principle.
In return for access to bases here, it still suits America to provide long-range maritime security for Japan (as well as nuclear security). But it isn't America's oil that comes from the Persian Gulf through East Asia's maritime chokepoints and marginal seas. And with the Cold War long over, forward deployments in this region are a matter of strategic choice rather than necessity for the United States. America's alliance with Japan is grounded in interest, not sentiment.
Japan's rationalization for signing the deal to develop the Azadegan oil field in Iran is that Tehran has now agreed to accept additional inspections from the International Atomic Energy Agency. But evidence is daily coming to light that Tehran has not come clean. The IAEA has discovered additional violations, with the latest connection being to a military airfield.