On the Korean Peninsula, June seems to be the cruelest month.

In June 1950, North Korean tanks rolled across the 38th Parallel, initiating the Korean War. In June 1994, tensions over Pyongyang's nuclear weapons program nearly led to war.

This June, tensions have risen to a high point once again. The North conducted its second nuclear test May 25, in violation of U.N. Security Council Resolution 1718. It has test-fired several missiles and rockets, some over Japan.

It has renounced the 1953 armistice that effectively concluded the Korean War. It has vowed to restart its plutonium separation facility at Yongbyon. Then last week it sentenced two American journalists who were reporting along the China-North Korea border to 12 years in a labor camp.

Even so, this is not a crisis. As Defense Secretary Robert Gates recently noted, North Korean attempts to influence negotiations through provocations are hardly unusual, and its military moves have not been out of the ordinary.

How did we arrive here?

In 1994 the Clinton administration negotiated the Agreed Framework. North Korea froze its five-megawatt reactor as well as plutonium separation at Yongbyon in exchange for the promise of two light water reactors, annual fuel deliveries, and humanitarian aid.

The North Koreans were believed to have one to two bombs' worth of fissile material, pre-dating the 1994 agreement, when the Bush administration took office in 2001.

In 2002, the White House accused the North Koreans of maintaining a covert uranium enrichment program of unknown scope and sophistication, setting off a chain of events that included: the collapse of the Agreed Framework, North Korean withdrawal from the Nuclear Non-Proliferation Treaty (NPT), and the reactivation of the Yongbyon facility. By the time the White House re-engaged North Korea in 2007, Pyongyang had perhaps as much as quadrupled its nuclear arsenal.

To address the North Korean challenge, we should recognize the diverse interests of our regional partners—China, Russia, Japan, and South Korea—and coordinate closely with them, including on intelligence-sharing.

China, which has the greatest influence over North Korea, and Russia want to avoid regional instability. China fears Japan developing an independent nuclear deterrent in response to North Korean bellicosity. Additionally, Beijing fears the potential flood of refugees into China that the collapse of North Korea would unleash, as well as a reunified Korea allied with the United States.

For South Korea, the possibly $1 trillion cost of reunification and the integration of one of the world's most backward economies into one of its most advanced is of major concern. Seoul also has security concerns.

What should the United States do? First, we should not rush our response, which should be forceful, but low key.

Our long-term goal remains the peaceful transition to a nuclear-free and unified Korean peninsula. In the short term, we should dispatch a special envoy to demand the release of the American prisoners.

Additionally, we should aim to get back to bilateral and Six-Party negotiations with realistic expectations and possibly an expanded agenda, re-introduce nuclear inspectors, contain North Korea through re-energized deterrence, demand that North Korea halt further plutonium separation, and act to prevent the transfer of nuclear technology to other states.

Tougher U.N. Security Council sanctions should be imposed and enforced, but their effectiveness largely will depend on Chinese cooperation. Sanctions should include banning arms exports, inspections of all suspicious cargo, blocking luxury imports, freezing North Korea's overseas bank accounts and denying North Korea access to financial assistance, banking and financial services, and low-interest loans.

We must confront North Korea with a choice: It can keep its nuclear weapons and endure isolation, or it can give up the nuclear weapons and begin the process of rejoining the international community.

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• Read Lee Hamilton Commentaries on foreign policy and Congress