A raft of Democratic lawmakers, led by the chairs of House committees that control nuclear weapons budgets and policy, on Monday demanded that the Department of Energy and the Pentagon explain recently reported discussions about resuming nuclear explosive tests.

The powerful House committee leaders want written answers to six questions by June 22 and a briefing from the agencies by June 25, according to their letter, which was printed on congressional stationary and dated June 8, 2020. The Washington Post reported prior to Memorial Day that the Donald Trump administration discussed conducting a “rapid” nuclear-explosive test, in part as a means of inducing Russia and China to negotiate a trilateral nuclear arms-control deal.

The same day the Democratic lawmakers made their letter public, the Senate Armed Services Committee’s Strategic Forces Subcommittee marked up the nuclear-weapons parts of the upper chamber’s 2021 National Defense Authorization Act, which sets policy and spending limits for DOE and Pentagon programs. The subcommittee didn’t release the bill text.

It was also the same day that Bloomberg reported that Russian and U.S. officials planned to discuss nuclear arms control on June 22 in Vienna.

“Resuming testing would open the door for widespread global testing, which would only serve to benefit our adversaries and make Americans less safe,” reads the committee leaders’ letter to Secretary of Energy Dan Brouillette and Secretary of Defense Mark Esper. The heads of the House Armed Services and Appropriations Committees, plus the chairs of subcommittees that write the nuclear-weapons parts of each year’s major defense policy and spending bills, all signed the letter.

Among other things, the lawmakers asked: whether the National Nuclear Security Administration’s (NNSA) program of no-yield, subcritical testing and supercomputer simulations was no longer adequate to certify that U.S. nuclear weapons work as intended; how the Trump administration intended to pay for a nuclear explosive test; and whether there has “been any independent assessment requested by the Departments of Energy or Defense of the need, cost, and impact of resuming nuclear testing, including supercritical testing.”

The Trump administration wants to negotiate a new trilateral nuclear arms control agreement with Russia and China to replace the New START agreement between the U.S. and Russia, which will expire in February if the U.S. and Russian presidents do not extend it for five years. New START, ratified during the Obama administration, limits Washington and Moscow to 1,550 the number of strategic nuclear weapons that Washington and Moscow may deploy on a mixture of intercontinental ballistic missiles, heavy bomber aircraft, and submarine-launched ballistic missiles.

Signing the House-side letter were: Rep. Adam Smith (D-Wash.), chair of the Armed Services Committee; Rep. Nita Lowey (D-N.Y.), chair of the House Appropriations Committee; Rep. Jim Cooper (D-Tenn.), chair of the Armed Services Strategic Forces Subcommittee; Rep. Marcy Kaptur (D-Ohio), chair of the Appropriations Energy and Water Subcommittee; and Rep. Peter Visclosky (D-Ind.), chair of the Appropriations Defense Subcommittee.

A separate letter garnered signatures from a bi-cameral group of almost 80 Democrats, who urged the administration not to resume nuclear-explosive tests. Sen. Ron Wyden (D-Ore.) and Rep. Bill Foster (D-Ill.). Wyden is the ranking member on the Senate Energy and Natural Resources Committee. Foster is the only PhD physicist in Congress.

“A return to nuclear testing is not only scientifically and technically unnecessary but also dangerously provocative,” reads the letter signed by many of the Democrats on the two chambers’ Armed Services Committees. “It would signal to the world that the U.S. no longer has confidence in the safety, security, and effectiveness of our nuclear weapons.”