WASHINGTON (AP) — The Trump administration took a key step Wednesday toward preserving the Obama-era nuclear deal with Iran, coupling the move with fresh ballistic missile sanctions to show it isn't going light on the Islamic republic.

The State Department said Iran would continue to enjoy relief from decades-old economic measures punishing Tehran for its nuclear program. Under the 2015 nuclear agreement, the U.S. lifted those sanctions. But Washington must issue periodical waivers to keep the penalties from snapping back into place and the most recent one was set to expire this week.

Donald T...