North Korea put its missile units on standby on Friday, and the country's leader, Kim Jong Un, threatened to "settle accounts" after the United States flew nuclear-capable stealth bombers over the Korean peninsula as part of South Korean military drills.
According to the official North Korean news agency, Jong Un signed a rocket preparation plan at midnight and ordered troops on standby for a potential strike against South Korea or the United States.
The Korean leader "judged the time has come to settle accounts with the U.S. imperialists in view of the prevailing situation," according to a translation of the KCNA report provided by Reuters.
Secretary of Defense Chuck HagelChuck HagelLobbying World Ex-Dem leader: Clinton should include GOP in Cabinet Even Steven: How would a 50-50 Senate operate? MORE said Thursday that the provocations were "very dangerous."
"We must make clear that these provocations by the North are taken by us very seriously and we'll respond to that," he told reporters at the Pentagon.
Earlier Thursday, the White House confirmed that a pair of B-2 bombers had participated in military exercises with the South Korean military.
White House spokesman Josh Earnest described the drills as "defensive in nature," but issued a stern warning to the North Koreans.
"In the face of the bellicose rhetoric and threats that have been emanating from the North Koreans, is that we stand shoulder to shoulder with our allies in South Korea to ensure that the interests of the United States and the allies of the United States remain protected," Earnest said.
"And that is something that should be evident from the comments of senior administration officials, but should also be evident from the close security cooperation that we have with the South Koreans, including these recent military exercises."
Despite aggressive posturing from the North, few international experts believe that military conflict is likely.
North Korea's long-range missile capabilities remain untested, and the White House has said previously that it does not believe the country's long-range missiles are a threat to the American homeland.
While the North Koreans do have capable short-range missiles that could threaten South Korean civilian and military targets, North Korea is also heavily reliant on trade within the joint economic zone.