The natural state of the Korean peninsula is one country, not two, and the Korean people should have the opportunity to live in democracy and freedom under one flag. But North Korea’s missile test last Wednesday brings into focus just how far apart the two nations have grown.

On the one hand, South Korea is a prosperous and vibrant democracy and a major player in the Asian economy. On the other hand, North Korea is a failed state ruled by a desperate dictator who starves his own people while pursuing a nuclear arsenal.

North Korea is killing its own citizens as it fails and it destabilizes an already volatile region. Long-range missile capabilities would extend this influence further, possibly even directly threatening America. To make matters worse, Kim Jong Il’s need to raise money for his regime could lead him to sell nuclear materials to terrorists.

The problem is not only that the North Korean regime possesses dangerous weapons, but also that the regime itself is unstable and dangerous. If we focus only on containing weapons programs, we will not solve the root of the problem, which is the regime itself. We should not simply treat the North Korean regime as a permanent feature of the geopolitical landscape. Instead we should set a longer-term goal to spread democracy across the entire Korean peninsula.

Years of fruitless negotiations demonstrate the folly of trying to change Kim’s behavior. A man who maintains Stalin-style death camps and who starves his own people in pursuit of nuclear missiles is not a credible negotiating partner. We must continue to work with our regional allies to maintain a credible deterrent to North Korean aggression while pursuing missile defenses that undercut North Korea’s latest threats.

But as we have seen in the past, if security is the only topic of conversation, we hold ourselves hostage to a brutal dictator’s periodic cries for attention. Given that North Korea is collapsing, we should encourage China and South Korea to take a longer-term view and begin laying the groundwork now for a free and democratic peninsula.

This goal will require China to choose between siding with the free world or its increasingly unstable neighbor. To date, China has underwritten North Korea’s very existence as a hedge against instability. But as the missile tests prove, even China’s enormous economic assistance program is insufficient to keep North Korea under control. In the long run, China will find greater stability with a Korean peninsula free of Kim’s dictatorship.

While North Korea is facing external diplomatic pressure, we can pressure the regime from within by shining more light on its human rights abuses and by accepting North Koreans into America as refugees.

Under the provisions of the North Korean Human Rights Act, which passed the Senate in 2004, this past May six North Koreans were admitted into America as refugees for the first time since the Korean War ended nearly 50 years ago. I met with them in my office and heard their heartbreaking stories of imprisonment, sexual slavery, torture, and abuse. Hearing their stories was one of the most moving experiences of my life. They have hope because they are now living lives of freedom in America, and I hope that more North Koreans can follow them here.

Much like the Soviet Union collapsed under the weight of its own moral illegitimacy, we can pressure the North Korean regime by providing its brutalized citizens with an opportunity to flee and a place to go. While it is relatively easy for North Koreans to escape their regime and flee to China, once in China it is difficult for them to evade authorities and move on to safe haven elsewhere. In concert with our diplomatic efforts to pressure the regime from the outside, we can pressure it from within by encouraging China and other nations to help North Koreans flee to South Korea, America, or other nations.

This latest crisis is not the first or last time we’ll be faced with North Korea’s recalcitrant approach to world affairs. We need to act now and keep up the pressure before North Korea sacrifices more of its own people in pursuit of missiles and nuclear weapons. We can keep security threats in perspective by unabashedly promoting democracy and human rights for the North Korean people and providing care and relief for those who escape the regime. This combination of external and internal pressure is the best way to lay the groundwork for freedom, stability, and growth in the Korean peninsula and throughout the region.

Mr. Brownback is a senator from Kansas and the chairman of the Helsinki Commission.