North Korea probably has the capability to build a nuclear warhead that can be mounted on a ballistic missile, the commander of U.S. forces in South Korea said Friday. However, he added that since the country has not tested the weapon, the chances of it being effective were low.

Speaking to reporters at the Pentagon, Army General Curtis Scaparrotti said that North Korea's connection with Iran and Pakistan meant it possibly had access to the know-how needed to miniaturize and mount a nuclear weapon on a missile, according to Reuters.

"Personally I think that they certainly have had the expertise in the past," Scaparrotti said. "They've had the right connections, and so I believe they have the capability to have miniaturized a device at this point, and they have the technology to potentially actually deliver what they say they have."

"We have not seen it tested. And I don't think as a commander we can afford the luxury of believing perhaps they haven't gotten there," he added, reports the Associated Press.

Elaborating further, Scaparrotti said that North Korea's parading of the road-mobile missile launcher and KN-08 intercontinental ballistic missile was a matter of concern. He also said that there was no sign of disorder in North Korea when leader Kim Jong-un disappeared from public view for many weeks.

The Pentagon press secretary, Rear Admiral John Kirby, said later that Defense Secretary Chuck Hagel shared Scaparrotti's concerns about North Korea's attempts to acquire a nuclear weapon. However, he added that the general has not said that North Korea was capable of mounting the weapon on an intercontinental ballistic missile.

"General Scaparrotti said he believes they have the capability to miniaturize," Kirby said. "That's not the same thing as saying that they have the capability to mount, test and deliver a nuclear weapon in an ICBM," he said, reports Reuters.

The United States does not have formal relations with North Korea. It has stationed more than 28,000 troops in South Korea, intended to prevent an attack by North Korea on their southern neighbors.

On Thursday, The United States and South Korean defense chiefs formally scrapped a 2015 deadline for handing over full control over Seoul's military from the United States to South Korea.