An unarmed AGM-86B Air-Launched Cruise Missile is released from a B-52H Stratofortress over the Utah Test and Training Range during a Nuclear Weapons System Evaluation Program sortie, 80 miles west of Salt Lake City, Utah, U.S., Sept. 22, 2014. (Xinhua/REUTERS)

WASHINGTON, Feb. 7 (Xinhua) -- The recently released U.S. Nuclear Posture Review (NPR) calling for an expansion of America's nuclear arsenal will endanger the world, a U.S. expert said Wednesday.

"This is an unhelpful strategy that's going to make the world's nuclear danger greater, not smaller," Daryl Kimball, executive director of the advocacy group Arms Control Association, told Xinhua.

The U.S. nuclear policy expert pointed out that the NPR, which is Washington's nuclear strategy, is seeking to elevate the status of nuclear weapons in the U.S. war chest, calling for new types of nuclear warheads and new capabilities.

Anti-nuclear war protesters sit in a hearing of the U.S. Senate Foreign Relations Committee about presidential authority to use nuclear weapons on Capitol Hill in Washington, Nov. 14, 2017. (Xinhua/REUTERS)

But the plan is based on inaccurate assumptions about the current strategic environment and will face hurdles in its implementation.

The 2018 NPR is starkly different from the last one published in 2010 under former U.S. President Barack Obama.

The 2010 paper saw the United States wanting to reduce the role and the importance of nuclear weapons. The fundamental role of nuclear weapons was to deter nuclear use against the United States and its allies. But the 2018 NPR goes in the other direction, Kimball said.

"It says that nuclear weapons may have a role not just (in) nuclear deterrence, but (in) the deterrence of non-nuclear strategic threats, including potential cyber attacks that affect the U.S. infrastructure or a conventional attack with strategic implications," he said.

"I think what the United States is doing unfortunately is making nuclear weapons usable... They are increasing the chance that nuclear weapons might be used in a conflict."

Kimball noted that the NPR assumes that other nuclear-armed countries are "getting ahead" with their nuclear capabilities, and the United States is not.

An aide carries a case containing launch codes for nuclear weapons, following U.S. President Donald Trump on the South Lawn of the White House in Washington, U.S., before his departure to Camp David, June 17, 2017. (Xinhua/REUTERS)

"The reality is that the United States and Russia have been replacing their Cold War nuclear weapon systems for some time ... The strategic situation is not radically different from what it was five, even 10, years ago," he said.

While the NPR states that the current U.S. nuclear strategy is not deterring enough and may spur Russia to use nuclear weapons first in a regional conflict to prevent U.S. intervention, Kimball dismissed the assumption.

"I think it's highly unlikely that Russia would use nuclear weapons in a conflict outside of Russia," he said, adding that there is sufficient deterrence to prevent Russia from doing so.

"I think the Pentagon's assertion that Russia has a strategy to use nuclear weapons first in a regional conflict is debatable at best and I think there's also evidence that they may be wrong about that. Either way it does not justify the pursuit of a new low-yield U.S. nuclear capability," he said.

Should the Pentagon follow through on the NPR, Kimball predicted it will face legislative and financial hurdles.

"There will be political opposition to this. There are a number of Democrats who raised serious questions about developing new nuclear weapons capabilities," he said.

"In addition, the price tag for the U.S. nuclear weapons program is already enormous ... If you add these new capabilities on top of that, that's even more money that is going to have to come from somewhere."

The best way to navigate forward is through dialogue, the expert said.

"What's important here is for the United States and Russia, and the United States and China to enter into regular strategic stability discussions to better understand the nuclear strategies of one another," he said.