In 2009, President Barack Obama delivered a speech at Hradcany Square in Prague. There, he spoke of nuclear armament and the decreasing threat of nuclear war in a post-Cold War world. But despite the decreased threat, Obama said nuclear weapons had proliferated.

“To put an end to Cold War thinking, we will reduce the role of nuclear weapons in our national security strategy, and urge other to do the same, Obama said. “Make no mistake: As long as these weapons exist, the United States will maintain a safe, secure and effective arsenal to deter any adversary, and guarantee that defense to our allies…But we will begin the work of reducing or arsenal.”

In the wake of North Korea’s alleged hydrogen bomb test, The New York Times reports that the U.S. Energy Department and Pentagon have been taking a smaller approach to modernize nuclear weapons.

The report focuses on the B61 Model 12, “the first of five new warhead types planned as part of an atomic revitalization estimated to cost up to $1 trillion over three decades,” the media outlet reports. “As a family, the weapons and their delivery systems moved towards the small, the stealthy and the precise.”

Last year, the U.S. tested a mock version of the bomb in Nevada. In response, Russia Deputy Defense Minister Anatoly Antonov said, “It turns out that under the disguise of a notorious and invented threat coming from the Russian side, the United States was not only increasing the military potential and activity of NATO member states, but was upgrading its nuclear potential as well.”

However, Brian P. McKeon, the principal deputy under secretary of defense for policy, said Obama’s nuclear initiatives are progress towards a smaller force and safer world, The New York Times reports.

In 2010, the Obama administration released a plan to reduce the proliferation of nuclear weapons. “The United States will not develop new nuclear warheads or pursue new military missions or new capabilities for nuclear weapons,” Obama said.

Instead, the plan was to “rearrange old components of nuclear arms into revitalized weapons,” according to The New York Times. One of the results was the B61 Model 12, the force of which can be dialed down or up depending on the potential target.

The Federation of American Scientists said the B61 Model 12 “violated” Obama’s 2010 Nuclear Posture Review. This “contradicts U.S. and NATO goals of reducing the role of nuclear weapons and could undermine efforts to persuade Russia to reduce its non-strategic nuclear weapons posture.”

Andy Weber, the former secretary of defense, and William J. Perry, a secretary of defense under President Bill Clinton, criticized the new cruise missile. “With the updated B-2 and B61 expected to remain in service for many decades, and the planned deployment of new B-3 penetrating bombers with B61 bombs starting in 2025, there is scant justification for spending tens of billions of dollars on a new nuclear air-launched cruise missile and related warhead life-extension program,” they wrote in The Washington Post.

According to Sandia National Laboratories, at the end of 2014, the U.S. had around 4,717 warheads in its stockpile. That number peaked during the Cold War at 31,255. “We’re not designing any new systems—new warheads, new nuclear bombs—with new military capabilities. What we are doing is just taking these old systems, replacing their parts, and making sure that they can survive another period of time,” said Madelyn Creedon, the Energy Department deputy administrator, in October.