North Korea's latest missile firing was a wake-up call for the U.S. military on several fronts, according to top military officers.
On Monday, North Korea fired four missiles that ended up falling into the ocean off Japan. The event showed the rogue nation may be getting closer to its goal of having a nuclear-armed ballistic missile capable of reaching the U.S.
The development comes as the U.S. military is relying on an aging command and control system that helps military leaders obtain and process information in times of nuclear threats, such as enemies firing warheads. Moreover, there's an added risk since one of the early warning missile sensors used by the U.S. military is in space, which also is seen as increasingly vulnerable.
"We were up most of the night watching the North Korean launches of SCUDs [or missiles]," U.S. Air Force Gen. John Hyten, commander of the U.S. Strategic Command said in testimony Wednesday before the House Armed Services Committee.
Fortunately, the general said the early warning systems that are part of the nation's command and control of nuclear forces found that the latest North Korea missile firings "did not present a threat to North America." Yet, he said, the U.S. military is increasingly relying on an aging command and control system, which he called "my biggest concern when I look out towards the future."
The U.S. military this week started deploying the Terminal High Altitude Area Defense (or THAAD) anti-missile system in South Korea in response to missile threats from North Korea. THAAD, which has already been used in other regions of the world, is manufactured by Lockheed Martin.
Wednesday's hearing, entitled "Military Assessment of Nuclear Deterrence Requirements," focused on current global threats including efforts to modernize the nation's nuclear arsenal and nuclear command and control capabilities.
Hyten told the congressional panel that the nuclear command and control area is his "number one priority inside the modernization piece. Everything we have today works very effectively. But it is very resilient, robust and ancient. Ancient is the concern."
Similarly, outside experts recently told CNBC more focus should be placed on command and control systems, including satellite and other communication systems with nuclear forces as well as how the military gets early warnings of an incoming strike.
The U.S. military uses what's known as an Integrated Tactical Warning/Attack Assessment (ITW/AA) system, which includes missile warning radars and space-based sensors that provide a picture of threats. The information comes into the nation's command and control, thereby giving the president, the Defense secretary and military leaders key information when deciding how to respond to threats.
However, experts speaking at the Wednesday panel said the space-based portion of the early warning and attack assessment system maybe vulnerable.
House Armed Services Committee Chairman Mac Thornberry, R-Texas, asked the military leaders about reports that other nations are trying to deny the U.S. the capability to operate in space and from space, which the congressman indicated has "implications for our strategic deterrence."
"When you look at what adversaries are doing, they are clearly building capabilities to deny us [capability to operate from space],' said Hyten. "Some of those capabilities could go after our strategic early warning systems."
By going after space assets, it could potentially deny the U.S. visibility into actions of adversaries such as preparing to launch missiles or the actual launch of weapons. China is believed to be one nation increasing its research and development spending in this area although there are others.
Rival nations "should know we are watching very, very closely and we are developing capabilities to allow us to continue to fight through and respond to any attack that would come into the space domain now or into the future," Hyten said.
Air Force Gen. Paul Selva, vice chairman of the Joints Chiefs of Staff, testified that enemies launching strikes against U.S. space assets also are creating "ambiguity that's not helpful in terms of nuclear deterrence on both sides of the equation."
Elsewhere, the hearing also touched on the disparity between the U.S. and Russia in terms of non-strategic nuclear weapons.
Military leaders pointed out that for the past two decades U.S. policy has called for the reduction of nuclear weapons and forces; however, in this same period of time they said nuclear rivals have not followed the U.S. example.
According to Selva, adversary nations have instead increased their reliance on nuclear weapons, improving their capabilities and in some instances expanding their nuclear stockpiles.
The U.S. military leaders were asked about the size of the Russian arsenal. "The Russian numbers are huge and our numbers are small," responded Hyten.
When asked about U.S. modernization of weapons versus others, Hyten responded: "I don't have a detailed insight into the nuclear weapon modernization in Russia or China, but I can tell you that they are across the nuclear enterprise ahead of us in some areas of modernization, behind in other areas. In general, we can still provide the effective strategic deterrent we have to in this nation, but we have to step forward quickly in the modernization realm here."
Selva said the U.S. has preserved its nuclear deterrent by extending the lifespan of what he termed "legacy nuclear forces and infrastructure," including sometimes for decades beyond what he said was originally intended. "But these systems will not remain viable forever," he said. "Nuclear modernization can no longer be deferred."
Indeed, Selva cautioned against any future disruption in nuclear modernization.
"Any disruption in the current program of record for future acquisition plans will introduce the risk — a significant risk — to our deterrent," said Selva.
The House hearing also provided updates for key programs involving the nation's nuclear triad, which includes land, sea and air elements.
For example, the new B-21 long-range strike bomber under development by Northrop Grumman just finished preliminary design review, according to Air Force Gen. Stephen Wilson. "It's making great progress," he testified.
The B-21 stealth bomber will modernize the Air Force's aging bombers, including the B-52 built in the 1960s as well as the B-2, a stealth bomber made about 20 years ago by Northrop.
As for the Navy, the Columbia-class nuclear missile submarine, which replaces the Trident missile-armed Ohio-class, is running "on time and on schedule," according to Admiral Bill Moran, vice chief of Naval Operations.