President Trump has made no secret of his desire to isolate and impoverish Iran. After withdrawing last year from the nuclear deal negotiated by the Obama administration and five other nations, Mr. Trump launched his campaign of “maximum pressure” designed to change Iran’s behavior — and perhaps its leadership.

Mr. Trump dialed up the heat again last week by lifting waivers that had allowed eight countries (including China, India, South Korea and Turkey) to continue importing limited quantities of Iranian oil. Most of these countries have worked to reduce such purchases, but the Trump administration demanded that they end them outright or face American financial sanctions. On Thursday , Turkey said it couldn’t find other suppliers quickly enough to meet the deadline.

The goal, pressed most forcefully by the national security adviser, John Bolton, seems clear: to strangle Iran’s oil-dependent economy and lay the ground for regime change. Although Saudi Arabia has promised to stabilize the market by making up for Iranian oil losses, there is a risk the effort could backfire, triggering a hike in world prices.

Mr. Trump’s pressure tactics are having an effect. According to the International Monetary Fund, economic sanctions, reimposed by Mr. Trump after President Barack Obama lifted them when the nuclear deal was signed in 2015, have pushed Iran into recession and pushed its inflation rate to nearly 40 percent. Its economy is forecast to contract this year by 6 percent.