Secretary of State John Kerry tapped a former ambassador to Poland and career diplomat to lead U.S. efforts to implement the Iranian nuclear accord sealed between six world powers and Iran in July. Mr. Kerry’s pick, Stephen Mull, recently left his post in Poland and is a career foreign-service officer. He will be charged with working to ensure Iran and other partners comply with the steps laid out in the nuclear accord. At one point in his 33-year diplomatic career, he helped to design a U.N. Security Council resolution that enacted nuclear sanctions on Iran. In a statement announcing Mr. Mull’s appointment, Mr. Kerry said the Obama administration would work closely with allies “to deepen our security cooperation and to counter Iran’s destabilizing behavior, including its support for terrorism.” Mr. Kerry added: “These concerns and others related to Iran will continue to have the attention of the highest levels […]