Hurricane Katrina drove home the staggering devastation that disasters — natural or man-made –can inflict. Meanwhile, July’s attacks on the London Underground reminded us terrorists can still strike major world cities. Now imagine the two joined together: terrorists, armed with weapons of mass destruction, unleashing Katrina-scale chaos and death in the heart of a U.S. city.

Such attacks are hardly unthinkable. Roughly half of Russia’s weapons-grade nuclear materials are poorly protected. In the small Russian town of Shchuch’ye, nearly 2 million shells of VX and sarin nerve gas — each lethal enough to kill 85,000 people — lay stacked in chicken cooplike structures. The September 11 commission said al Qaeda has pursued getting and using these weapons as a “religious obligation” for more than a decade.

Fortunately, unlike hurricanes, much can be done to prevent this nightmare from becoming real. One of our first and best lines of defense is the Cooperative Threat Reduction (CTR) program, created by former U.S. Sen. Sam Nunn, Georgia Democrat, and Sen. Richard Lugar, Indiana Republican. Since 1992, the program has eliminated thousands of Russian nuclear warheads, missiles, submarines and bombers.

But in recent years, a set of burdensome congressional restrictions has marred the program and led to a series of disruptive stop-and-start cycles. Key projects vital to America’s security have ground to a halt for months on end because, for example, Russian human-rights obligations were not met or the paperwork to waive them was not completed.

Congress now has the chance to end such dangerous disruptions once and for all. Mr. Lugar, decrying those misplaced priorities, introduced language to repeal all the restrictions, which the Senate embraced by an overwhelming, bipartisan 78-19 vote in July. But until the full Congress approves it, CTR’s vital efforts remain in danger, from both a national security and a business perspective.

Danger of delay: Current restrictions carry real costs on the ground. In mid-2002, all new CTR projects — including security upgrades at 10 nuclear weapons storage sites — stalled for four months because the conditions could not be certified. Destruction of the Shchuch’ye stockpile was delayed some 15 months from 2001 to 2003 for similar red-tape reasons.

Such stoppages not only prolong threats to America, they also endanger the hundreds of millions of taxpayer dollars already invested in Shchuch’ye and other projects. So long as the conditions remain, these dangerous disruptions are inevitable.

Wasted resources: In a yearly drama, defense staffers and intelligence analysts must spend thousands of hours assessing Russian compliance with CTR restrictions — even when it is immediately clear Russia cannot meet them. Nor can the president simply waive the conditions without first submitting to this annual exercise in foregone conclusions.

Abetting such delays or allowing concerns like human rights, however important, to threaten human existence massively is the height of folly. We not only agree with Mr. Lugar that, during a war on terror, these artificial barriers “are destructive to our national security”; we see them undermining one of the best investments our country can make.

CTR, simply is good security on the cheap. At an annual cost of as little as one-tenth of 1 percent (0.001) of the Pentagon budget, the program has deactivated and helped guard 6,760 Russian nuclear warheads. It has upgraded security to the Shchuch’ye depot and similar sites. It also helped remove all nuclear weapons from Ukraine, Belarus and Kazakhstan.

Today, CTR continues upgrading security and aiding accounting of nuclear weapons transportation and storage. It also works to destroy biological weapons production facilities and lock down pathogen collections in Russia and the former Soviet republics.

CTR’s largest current project, eliminating the Shchuch’ye stockpile, will rid us of all 2 million of those weapons — and cost each American roughly the same as a large latte.

Nor is this money “foreign aid”: More than 80 percent of CTR funds go to five U.S. prime contractors that dismantle and destroy these weapons.

The risk of a Katrina-scale terrorist attack with Russian weapons is too critical to tolerate any delays to these crucial efforts. Congress must act and free us to meet what President Bush calls “the greatest threat before humanity today.”

Ted Turner is chairman of Turner Enterprises in Atlanta. Stanley A. Weiss is chairman of Business Executives for National Security, of which Mr. Turner is a member.