H.R. 5894: RESTRAIN Act

H.R. 5894, the “Renewing Efforts to Suspend Testing and Reinforce Arms-control Initiatives Now Act,” or “RESTRAIN Act,” would amend section 4210 of the Atomic Energy Defense Act, codified at 50 U.S.C. 2530. Its core rule is simple and sweeping: “No explosive testing of a nuclear weapon, or any other nuclear explosion, may be conducted by the United States.” That language covers both a nuclear weapons test and any other nuclear explosion, not just a specific weapons program.

The bill goes beyond a policy statement by adding a funding cutoff. It says funds authorized to be appropriated by an Act authorizing funds for fiscal year 2026, or funds otherwise made available for any fiscal year, cannot be used for explosive testing of a nuclear weapon or any other nuclear explosion. That matters because it tries to block both direct approval of testing and later attempts to finance a test through some other yearly funding stream.

At the same time, the bill preserves one important exception. It states that nothing in the new funding limitation restricts the authority of the United States to conduct a “subcritical nuclear test.” The bill defines that term specifically as a test of fissile materials that are not capable of sustaining an explosive nuclear chain reaction. In plain English, the measure bans explosive nuclear tests but still allows certain non-explosive experiments involving fissile material.

Politically, the bill signals a clear arms-control position in the Armed Forces and National Security space. With 26 cosponsors and an introduction date of 2025-10-31, the fight ahead is likely to center on whether Congress wants a permanent statutory ban on explosive testing, or whether future presidents and defense planners should keep that option available. The text itself is narrow and direct: no explosive testing, no federal funds for it beginning with fiscal year 2026, but subcritical tests remain legal.