The Trump administration has reportedly begun developing a new nuclear weapon, inching the U.S. closer to the possibility of a renewed arms race with Russia.

The low-yield weapon, called W76-2, is being built at the Pantex plant in Texas, according to NPR, which confirmed the Department of Energy’s work on the project via an email Monday. The weapon is a variation of the Navy’s submarine-launched W76-1.

The new weapon may yield from 5 kilotons to 7 kilotons, Hans Kristensen, director of the Federation of American Scientists’ nuclear information project, told NPR. That would be just under half the size of the bomb dropped on Hiroshima, which yielded roughly 15 kilotons.

The development of the new nuke is especially significant, since President Donald Trump stated in October that he intends to pull out of the Intermediate-Range Nuclear Forces Treaty, a 1987 arms-control pact made with the then-Soviet Union. The U.S has accused Moscow of breaking the agreement by using ground-launched intermediate-range missiles, which are prohibited. Russia has denied allegations of non-compliance.

A decision to suspend U.S. obligations under the treaty could arrive by this weekend, according to a White House official who spoke to Bloomberg News. A pullout, if announced, would take place over a six-month period.