The commander in charge of the United States’ nuclear forces told an audience in Washington on Thursday that those forces could “completely overwhelm” North Korea if it decided to attack the U.S.

“Our strategic nuclear forces completely overwhelm anything the North Koreans can bring to us, so if they want to attack the United States with nuclear weapons, it is not going to work out well for North Korea, it just won’t,” said Air Force Gen. John Hyten, commander of U.S. Strategic Command, at the Hudson Institute.

North Korea is working towards having a nuclear weapon that could hit the U.S. and has sped up its work this year trying to achieve that. In July, it launched two intercontinental ballistic missile tests, and earlier this month conducted its sixth nuclear weapons test.

The Trump administration is working on a diplomatic-led strategy to get North Korea to give up its nuclear weapons, including rallying international support and imposing more sanctions, but so far North Korea has remained recalcitrant.

In the meantime, Hyten said the U.S. has the “most robust deterrence” against any North Korean attack a nation could possibly have.

Hyten discussed the three legs of deterrence: The ability to impose “unthinkable” costs on an adversary, having the capability to deny the adversary the benefit of an attack, and making sure the enemy knows it.

“We have probably the most robust deterrence you can possibly have against a nation in our deterrent capability against North Korea,” he said

Hyten continued:

As we sit here today, we have soldiers in Alaska, and soldiers in California that are sitting alert with interceptors. We have sensors deployed in the Pacific and in Alaska, that will see and characterize that threat and provide that so we can shoot it down if it’s coming to the United States or Hawaii or Guam. We have the capabilities in order to do that, and the capabilities will work. It’s built to go against North Korea.

As far as whether the U.S. credibly conveys this all to North Korea, Hyten said, “That’s why we conduct the missions that we do. That’s why we talk the way we talk. That’s why you hear Secretary Mattis talk about what we have to do. That’s why you hear the president talk about what we have to do.”

Hyten said the deterrence also extended to its allies, demonstrated in the form of U.S. bombers and fighter jets flying with allies in the region.

“That’s why we fly B-1s, and B-52s and F-35s with our Japanese and Korean allies in that part of the world to make sure they understand we’re right there, we’re watching all the time, and if you want to go that way, we’re ready so we can deter an attack on North America or our allies,” he said.

“We want all the peaceful solutions to work,” he added.

Hyten clarified that nuclear deterrence against North Korea means deterring a nuclear attack from North Korea, not deterring them from decisions made internally, such as to build a nuclear weapon that can hit the U.S.

On that front, Hyten said North Korea has demonstrated it has all the elements of having such a nuclear weapon but has not demonstrated it has the ability to put those elements together and use it.

“The one thing they have not demonstrated to the United States is the ability to put everything together end-to-end, and use it,” he said. Hyten called the end game the “hardest part,” but said if North Korea continued down its current path, it would eventually figure it out.

“Will they get there in 2017, 2018, 2019? I don’t know the answer to that. I see a lot of detailed intelligence. I can honestly say I don’t know the answer to that question,” he said.

If deterrence against an attack from North Korea fails, Hyten said he was “very confident” the U.S. military could protect all 50 states from a nuclear attack, including Guam. At the same time, he said the U.S. could improve its military defense capabilities.

Hyten said:

Can we improve our missile defense capabilities? We can. We can do it by improving our sensor capabilities first. I think we need a space-based sensor capability as part of that to provide more ubiquitous global coverage. I think we need improved interceptors. I think we can improve that technology. We need better capacity, we need all those things and I’ve told the Congress that.

An impediment to improving those capabilities—and therefore, deterrence—is Congress’ lack of ability to deliver budgets by the first day of the fiscal year on October 1, he said.

Getting regular budgets make it easier to work with the defense industry, since it encourages companies to invest their own money in building a system first, knowing the government funding would come later, he said.

But having continuing resolutions (CR)—which extend the prior year’s funding to the prior year’s activities—makes it impossible to start new programs, and causes defense industries to go to private firms to develop new technologies, instead of work with the U.S. government, he said. The CRs are actually worse than the defense budget caps referred to as sequestration, he said.

“The CR is actually the worse thing. It’s worse than the caps,” he added. “Not having a budget by the first of the year just makes it hard for the [Defense] Department—for anyone—to plan.”

A slow acquisition process is also to blame, Hyten said. During the 1960s and 1970s, it would take several years to build a new system, but now it can take more than a decade, he said. He also criticized today’s risk-adverse weapons testing process that tries to avert failure, which he said makes it difficult to improve.

“We only learn from failure, we don’t learn from success,” he said. “If we have smallest glitch in any one of our test programs, it’s front page news.”

Failing is necessary to learn, and learn faster—something U.S. adversaries are doing, he said.

“When you fail, if you do it right, you go fast. And unfortunately, for the United States, our adversaries are doing that right now, and we are not,” he said.

Catch the full remarks below: