This is an archived article that was published on in 2006, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

Correction: Stories on April 6, 7 and 13 about the Divine Strake test at Nevada Test Site incorrectly reported that the explosion planned for June 2 will be five times larger than the largest conventional weapon in the U.S. arsenal. The explosion actually will be nearly 50 times bigger.

WASHINGTON - A powerful blast scheduled at the Nevada Test Site in June is designed to help war planners figure out the smallest nuclear weapon able to destroy underground targets. And it has caused a concern that it signals a renewed push toward tactical nuclear weapons.

The detonation, called Divine Strake, is intended to "develop a planning tool to improve the warfighter's confidence in selecting the smallest proper nuclear yield necessary to destroy underground facilities while minimizing collateral damage," according to Defense Department budget documents.

Irene Smith, a spokeswoman for the Pentagon's Defense Threat Reduction Agency, said the document doesn't imply that Divine Strake "is a nuclear simulation." She said it will be used to assess computer programs that predict ground shaking in a major blast.

While it will not be a nuclear explosion - no nuclear or radioactive material will be used - the Divine Strake blast will be fifty times larger than the military's largest conventional weapon, the Massive Ordinance Air Blast Bomb, or MOAB, nicknamed the Mother of All Bombs. It will still be many times less powerful than the smallest weapon in the U.S. nuclear stockpile.

"It seems like what they're doing is trying to use the explosive power to shake the interior into pieces, rather than sending an earth penetrator down to dig it up," said Hans Kristensen, a nuclear weapons expert with the Federation of American Scientists. "What it apparently does is envision the use of the nuke on the surface, and that is a very dirty business, because it sucks up the material and throws it into the atmosphere."

Divine Strake has some advocates concerned that the Bush administration is using the test to pursue development of low-yield, tactical nuclear weapons.

"We certainly have reason for concern," said Vanessa Pierce, a project director with Health Environment Alliance of Utah. "I think this test shows that the weapons designers are so obsessed with creating new nuclear weapons like mini-nukes that they'll do whatever it takes to get their fix."

"There really is a deep commitment on the part of this administration to creating new types of nuclear weapons," Pierce said.

Senate Minority Leader Harry Reid has expressed concern about the mushroom cloud the test will produce, and asked Defense Secretary Donald Rumsfeld for a classified briefing on Divine Strake. Reid is scheduled to meet with James Tegnelia of the Defense Threat Reduction Agency this afternoon.

The June 2 test will entail piling 700 tons of ammonium nitrate and fuel oil atop a buried limestone tunnel on the Nevada Test Site, then detonating it to measure the damage that would be done to the chambers.

The mixture that will be used is similar to the bomb that Timothy McVeigh used to blow up the Alfred P. Murrah federal building in Oklahoma City in 1995, only the Nevada bomb will use 280 times as much material.

Equipment inside and near the tunnel will monitor damage and ground shaking from the blast. Dust from the mushroom cloud, which could reach heights of 10,000 feet, will also be tracked.

J. Preston Truman, director of the group Downwinders, which represents individuals sickened by radioactive fallout from Cold War-era nuclear tests, scoffs at the Pentagon's suggestion that it is not a nuclear simulation, arguing no military plane could drop a 700-ton conventional bomb.

"It's for one thing and one thing only," he said. "It just says they're still pursuing these stupid, insane weapons."

The nuclear tie-in to Divine Strake test was rooted out by Kristensen and Andrew Lichterman, a nuclear weapons opponent and blogger.

"It's not a step toward nuclear testing. It is nuclear testing. It's just nuclear testing the way it's done today," since actual nuclear tests are banned by treaties, Kristensen said.

Similar above-ground detonations, some many times larger, have been conducted at White Sands Missile Range in New Mexico, according to planning documents for Divine Strake, but none since 1991.

The Defense Department's 2001 Nuclear Posture Review lays out a new, broader role envisioned for nuclear weapons than the part played during the Cold War.

"Non-nuclear strike capabilities may be particularly useful to limit collateral damage and conflict escalation. Nuclear weapons could be employed against targets able to withstand non-nuclear attack, (for example, deep underground bunkers or bio-weapon facilities)," the report says.

In addition, the Bush administration has pushed for funding for a nuclear bunker buster, and money to enable the Nevada Test Site to be able to test a weapon within two years if an order is given.

It has also supported the repeal of a 1994 congressional ban on the development of low-yield mini-nuclear weapons.

The ban was repealed by Congress in 2003, allowing research of low-yield nuclear weapons, but requiring specific approval by Congress before engineering or other work on mini-nukes can begin.