With North Korea demonstrating what appears to have been a successful launch of a submarine launched ballistic missile (SLBM), Pyongyang may have secured a nuclear second strike capability that could reduce the value of the American nuclear umbrella over Japan and South Korea. However, though the North Korean SLBM is not likely to pose a direct threat to the United States, it will create additional headaches for the U.S. Navy because the service will have to maintain track of Pyongyang’s ballistic missile submarines.

“This development would potentially give the DPRK [Democratic People’s Republic of Korea] a relatively secure second-strike capability. This could reduce the value of the U.S. nuclear deterrent against the North Koreans,” Bryan Clark a senior naval analyst at the Center for Strategic and Budgetary Assessments told The National Interest. “That would be significant, particularly in relation to our extended deterrence assurances to Japan and the RoK [Republic of Korea]. If the DPRK were to threaten one of them with nuclear attack, the U.S. could not effectively deter the DPRK by threatening a nuclear attack on it. The DPRK could still plan to launch the strike with its SSBN.”

The volatile North Korean regime has made many unsuccessful attempts to launch a SLBM—until Aug. 23. Late in the evening that day, the U.S. Pacific Command (PACOM) announced that American forces had monitored a successful North Korean SLBM launch at sea. “U.S. Strategic Command (USSTRATCOM) systems detected and tracked what we assess was a North Korean submarine missile launch at 3:29 p.m. CDT, August 23, 2016. The launch of a presumed KN-11 submarine-launched ballistic missile occurred off the coast of Sinpo. The missile was tracked over and into the Sea of Japan, approximately 300 miles off the coast of North Korea,” reads a statement issued by PACOM spokesman Commander Dave Benham. “The North American Aerospace Defense Command (NORAD) determined the missile launch from North Korea did not pose a threat to North America.”

As usual, PACOM issued a strongly worded condemnation of the North Korean test—and as usual—Pyongyang ignored it. “We strongly condemn this and North Korea's other recent missile tests, which violate UN Security Council Resolutions explicitly prohibiting North Korea's launches using ballistic missile technology,” Benham said. “This provocation only serves to increase the international community's resolve to counter the DPRK's prohibited activities, including through implementing existing UN Security Council sanctions. Multiple U.N. Security Council resolutions require the DPRK to suspend all activities related to its ballistic missile program.  We intend to raise our concerns at the UN to bolster international resolve in holding the DPRK accountable for these actions.”

Additionally, Benham said that the American commitment to Japan and South Korea is absolute and ironclad, but as Clark noted—the successful North Korean test unavoidably weakens the U.S. extended nuclear deterrence umbrella over those two nations. “Our commitment to the defense of our allies, including the Republic of Korea and Japan, in the face of these threats, is ironclad. We remain prepared to defend ourselves and our allies from any attack or provocation,” Benham said. “We call on North Korea to refrain from actions that further raise tensions in the region and focus instead on taking concrete steps toward fulfilling its commitments and international obligations.”

Though the North Korean SLBM will likely reduce the value of America’s extended deterrence over Japan and South Korea, the new weapons won’t be a huge problem for the United States’ own strategic nuclear deterrent. “The SSBN is less of a challenge for U.S. nuclear deterrence. If North Korea were to attack the United States directly, it would not be able to eliminate any leg of the U.S. nuclear triad and the attack could be small enough to be defeated by U.S. missile defenses,” Clark said. “The United States could then launch a devastating retaliatory strike. The fact the DPRK might be able to respond with a small number of SLBMs against the U.S. afterward would not be a deterrent on the U.S. response.”

That being said, the North Korean ballistic missile submarines which carry those SLBMs might prove to be a headache for the U.S. Navy’s dwindling attack submarine force, which is set to drop to a low-point of 41 by 2029—well below the required 48 boats (which is already set too low). “The DPRK SSBN may also introduce a new requirement to find and track it with U.S. SSNs, as we did against the Soviets during the Cold War,” Clark said. “The SSBN, however, will likely be fairly noisy and would likely not have the reliability and condition to deploy for long periods far from home. That would make them easier to find and track.”

Thus, while the North Korean development is significant—it’s probably not an insurmountable problem for the United States. Nonetheless, given a new SLBM force, Pyongyang might be emboldened to act even more belligerently than before.

Dave Majumdar is the defense editor for the National Interest. You can follow him on Twitter: @davemajumdar.