Sanctions on Iran, and Diplomacy International economic pressure is certainly necessary to contain Iran's nuclear ambitions, as "Iran and the Strait" (editorial, Dec. 30) argues. United Nations sanctions have slowed Iran's nuclear and missile efforts, buying valuable time and negotiating leverage. But pressure alone cannot succeed in forcing Iran's leaders to reverse course and could lead to further threats and provocations from Tehran. Keeping all options on the table should mean more energetic and American-led creative diplomacy aimed at convincing Iran's current and future leaders that they stand to gain more from forgoing nuclear weapons than from any decision to build them. President Obama entered office seeking to pressure and engage Tehran. Iran's fraudulent 2009 election and internal power struggles have undermined his engagement efforts, leading the Obama administration to ease off efforts to engage Iran. With pressure at an all-time high, President Obama should rebalance his approach by renewing discussions on a step-by-step process that leads to more intrusive inspections by the International Atomic Energy Agency and the confidence-building steps that are essential to prevent a nuclear-armed Iran, like a halt to enrichment of uranium above normal reactor fuel grade. If Iran is unwilling to agree to common-sense, confidence-building steps required to ease the sanctions regime, Tehran will remain isolated. A resolution to the nuclear crisis, however, requires pragmatic engagement. President Obama and other key leaders must keep testing Iran's willingness to change course by taking the diplomatic offensive. DARYL G. KIMBALL Executive Director Arms Control Association Washington, Dec. 30, 2011