US Military Developing 'Variable Nukes': Report

Current bombs already have or can be set to low yields of 20 kilotons, meaning an explosion wouldn't even touch an area a mile or so from the location of the detonation.

The new 'mini nukes' would offer the President 'a new option' military bosses say.

Some of the military's current bombs could be converted into this type of weapon, according to Hans Kristensen, director of the Nuclear Information Project at the Federation of American Scientists.

He added that it might be building more from scratch as well.

While the Cold War led to the motto of 'the bigger, the better,' US defense officials now believe the future of nuclear weapons is smaller ones that would actually be used. 

"If the only options we have are to go with high-yield weapons that create a level of indiscriminate killing that the President can't accept, then we haven't presented him with an option to respond to a nuclear attack in kind," Air Force Gen. Paul Selva, the Vice Chairman of the Joint Chiefs of Staff, said Thursday at a Mitchell Institute event in Washington D.C. according to Defense One

He said the US needs to be able to launch a nuclear attack without ending the world or causing massive 'indiscriminate' casualties.

"If all you have is high-yield weapons to answer a low-yield attack, it's still a nuclear attack," he said.

"Answering that with a conventional weapon is likely not going to have the kind of deterrent value as saying."

The move to develop 'mini nukes' is part of the modernization of the military's nuclear arsenal.

Last year, the Defense Science Board urged the Pentagon to incorporate more low-yield weapons and vehicles.

Selva said the Air Force has not reached a decision on that, but it is working to define new requirements for an intercontinental ballistic missile.

"Whether we do it with a ballistic missile or re-entry vehicle or other tool in the arsenal, it's important to have variable-yield nukes," he said.

The plan to focus on smaller nuclear weapons, however, has been scrutinized by some members of Congress who feel the move would attract scrutiny.

"I have no doubt the proposal to research low-yield nuclear weapons is just the first step to actually building them,' Sen. Dianne Feinstein, D-Calif, told Roll Call in February.

"I've fought against such reckless efforts in the past and will do so again, with every tool at my disposal."

She added: "There's no such thing as limited nuclear war, and for the Pentagon's advisory board to even suggest such a thing is deeply troubling."

Kirsetensen is skeptical too.

"The still-unanswered question is why there would be a need for a low-yield warhead on ballistic missiles," he said.

"What are the strikes that existing warheads can't do, where would the President be self-deterred because of too big yield, where has the intelligence community concluded that adversaries would get an advantage and deterrence (or war fighting) would fail if we didn't have low-yield, and why can existing capabilities not adequately hold at risk the same targets? Many questions, few answers."

Russia - which holds the largest nuke ever, the 1000,000 kiloton Tzar Bomba - has also experimented with smaller, more tactical versions.  

North Korea claimed to have tested a similar bomb, but clocking in at only 10 kilotons, it was considered to be more like a typical fission bomb.

But the Air Force's commitment to smaller nukes doesn't mean the military is forgoing big weapons.

In March, is was revealed the US Army has considered arming itself with a 'devastating' weapon, called the Kinetic Energy Projectile (KEP), in a bid to counteract Russia's nuclear technology.

The tungsten-based warhead is capable of moving three times the speed of sound, while destroying everything in its path.

Once launched, the missile bursts into flaming metal fragments that can pierce through most armor - such as that used in tanks.

Reports have noted that the Russian president is hording weapons four times more powerful than the US's `Mother of All Bombs´ that killed 36 ISIS (also known as Daesh) militants in Afghanistan last week.

With this knowledge, the Army on the hunt to find its own 'super-weapon' - which has lead them to KEP.

"Think of it as a big shotgun shell," Major General William Hix, the Army's director of strategy, plans & policy, said at the Booz Allen Hamilton Direct Energy Summit, Patrick Tucker with Defense One reports.

However unlike a shell, Hix said, the KEP travels at unbelievable speeds of 'Mach 3 to Mach 6.'

During the warhead's first test run in 2013, the sled train it was attached to exceeded 3,500 feet-per-second - three times the speed of sound.

Hix also revealed details to Defense One regarding the level of devastation this weapon would cause.

"Not much can survive it. If you are in a main battle tank, if you're a crew member, you might survive but the vehicle will be non-mission capable, and everything below that will level of protection will be dead," he said.

The Army has suggested attaching the KEP to its existing launch platforms, as they are able to take the brunt when the weapon is fired.

The warhead was first tested in 2013 at Holloman Air Force Base in New Mexico, which the Defense Department deemed a success.

During an interview with American Forces Press Service following the testing, Susan Hurd, special assistant to the director of strategic warfare, called the test significant technology development advancement.

'The successful execution of this high-speed sled test of a Kinetic Energy Projectile warhead was a necessary step in the progression to a conventional prompt strike capability,' she said.

"Now that we've demonstrated that the warhead functions in a flight representative environment we're one important step closer to that goal."

"High performance computer modeling and simulation as well as a series of small scale and static tests have already been done on this warhead."

"But in order to assess its performance in flight conditions you have to do the dynamic test – you have to do the sled test. Hurd emphasized this test was 'critical' in order to subject the warhead to the 'dynamic environment it would see in flight."

"The sled test was designed to be representative of conditions of flight and target engagement for the warhead."

Currently, the KEP is still in the conceptual phase, as the US military has yet to take over the project, a US Army spokesperson told Newsweek.