''A real and clear danger," is how Defense Secretary Chuck Hagel on April 3 described North Korea. Secretary of State John Kerry and South Korea Foreign Minister Yun Byung-se held a joint press conference in Washington to emphasize a military and security partnership.
They are reacting to North Korea declaring a "state of war" with South Korea and threatening nuclear attack. Pyongyang's seemingly demented declarations from the top have been echoed in some ominous moves. That government abruptly abrogated the 1953 armistice agreement ending the Korean War, and cut the military hot line communications link with the south.
Satellite images reveal that construction activity apparently has commenced at the Yongbyon nuclear complex. The facility was partially disabled in 2007 as the result of a diplomatic agreement.
Pyongyang is preventing South Korean workers from entering the Kaesong industrial center, located six miles north of the DMZ separating the two nations. The center is an important surviving source of hard currency vital to the feeble economy of North Korea.
These developments may presage war, a terrible possibility, yet there is still no concrete evidence that North Korea is mobilizing to invade South Korea. Moreover, Pyongyang's nuclear military capabilities remain rudimentary. Missile tests have included some limited success, but also dramatic failure.
More likely, there is a behind-the-scenes struggle for power. Last July, Vice Marshal Ri Yong-ho, a powerful figure, was relieved of command, allegedly due to illness. This explanation is generally discounted. He had been an ally of Kim Jong-un, North Korea's young and inexperienced leader.
Last May, Kim publicly criticized those in the military "developing a taste for money" amid reports of corruption. As part of the shakeup that followed, Kim assumed the rank of Marshal of the People's Army, the latest celebratory title sycophants have attached to his name. Whether he is solidifying power, or being weakened and sidelined, is not at all clear.
For several years North Korea has been acting erratically in military matters. In March 2010, a North Korea torpedo sank the South Korean ship Cheonan. In the same vicinity in November of that year, North Korean artillery bombarded South Korea's Yeonpyeong Island.
In late February 2012, North Korea agreed yet again to cease its on-again, off-again nuclear program. In joint announcements coordinated with the State Department, the regime agreed to halt enrichment of uranium and construction of weapons and permit international inspection of nuclear facilities.
Yet two months later, Pyongyang tested a missile. The launch ended in embarrassing failure. This erratic behavior, now over a fairly lengthy period, strongly implies infighting at the top.
President Barack Obama's instinct for moderate language and international cooperation is welcome, but so is the current tough response to Pyongyang's irresponsibility. The growing isolation of the surviving communist state provides an opportunity for Washington to strengthen ties with Beijing and Moscow as well as Seoul.
During the height of the Cold War, President Dwight D. Eisenhower provided an important lesson in the realities of war. Stalled Korean War armistice talks were quickly, successfully concluded following extraordinary obliteration bombing of North Korea. Ike knew how to get the most terrible yet essential jobs done, ruthlessly.
We must complement strong, mature public statements with our own preparations for military strikes, if such prove necessary. We must continue skillful diplomacy but be ready to act.