For the first time in decades, a U.S. president is threatening to restart nuclear weapons testing — a dangerous and unnecessary move that would put countless lives, communities, and even our planet at risk.

Past U.S. nuclear tests — including above-ground tests conducted decades ago from Nevada to New Mexico to the Marshall Islands — spread radioactive fallout that poisoned entire communities and ecosystems, leaving a legacy of cancer and contamination that continues today. And while testing methods have changed, restarting any type of explosive tests today would knowingly recreate that suffering and shatter the global taboo that has helped keep our world safe for more than 30 years.

Experts agree that there is no military or technical justification for explosive nuclear weapons testing, but there are potentially devastating consequences if we test again. Other countries have already signaled that if the U.S. resumes nuclear weapons testing, they will follow suit, further fueling the global nuclear arms race now underway.

Congress has the power to stop this — they can block any funding that would allow explosive nuclear weapons testing to resume. This issue is too important to our future for our elected officials to stay silent.