"We've seen reports of a new and unconstructive statement from North Korea. We take these threats seriously and remain in close contact with our South Korean allies," said Caitlin Hayden, spokeswoman for the White House National Security Council.
"But, we would also note that North Korea has a long history of bellicose rhetoric and threats and today's announcement follows that familiar pattern," she said.
The United States flew two nuclear-capable stealth bombers over the Korean peninsula as part of a military exercise this week in a show of force to reassure US allies in the region.
The Pentagon has also been beefing up US missile defense capabilities on the West Coast. The United States has been stressing that it has the capability and willingness to protect itself and U.S. allies in the region.
"We remain fully prepared and capable of defending and protecting the United States and our allies," said Hayden. "We continue to take additional measures against the North Korean threat, including our plan to increase the US ground-based interceptors and early warning and tracking radar," and the recent signing of a South Korean-US counter-provocation plan.