"Nothing focuses the mind," Mark Twain might have said, "like the prospect of a North Korean ballistic missile launch." Indeed, the dramatic revelation that the North Koreans may be preparing to launch one of their Taepo Dong missiles over the Pacific, threatening such U.S. allies as South Korea, Japan and Taiwan, may have finally focused the minds of the Senate's most determined opponents of missile defense.

On June 22nd the Senate approved an amendment by Sen. Jeff Sessions (R.-Ala.), chairman of the Senate Subcommittee on Strategic Forces, to infuse an additional $45 million into the Pentagon's missile-defense program "to accelerate the ability to conduct concurrent test and missile defense operations." The possible launch of a long-range North Korean missile "that could even reach the U.S.," Sessions argued, "calls for us to move forward with [missile defense] deployment as well as testing."

The nuance here is that Sessions and his allies believe it is prudent to deploy whatever missile interceptors we have, even while in the developmental phase. Proper testing requires the creation of an intricate network of operational systems, giving an inherent (if limited) capability to respond in a crisis situation. According to Senate Armed Services Committee Chairman John Warner (R-Va.), while this strategy is highly unusual, our "total vulnerability" to the maturing threats in rogue nations such as North Korea and Iran requires nothing less. Predictably, most Democrats loudly object to this approach, arguing that the missile shield must first be certified as "100% operationally effective" before being deployed.

But those who appreciate even the limited protection afforded by the deployment of a partial shield will be heartened to learn that the Sessions Amendment passed 98 to 0.

Connoisseurs of the congressional debate over missile defense, however, were shocked at this unanimity. After all, ever since President Reagan first proposed it in 1983, liberals have resisted any and all efforts to develop, and deploy a viable missile defense with near-theological intensity. In fact, my colleague Baker Spring argues that this unyielding opposition has borne bitter fruit as President Bush contemplates his limited options with respect to that missile now sitting on the launch pad in North Korea.

Had President Clinton and Congress not abandoned the missile defense architecture first outlined in 1991 by the Bush Administration, our ability to intercept missiles such as North Korea's Taepo Dong or Iran's SHAHAB-3 would be measurably greater. Spring emphasizes that the architecture they proposed -- interceptors for both medium and long-range missiles, a more robust network of sensors, and space-based interceptors known as "Brilliant Pebbles" -- would have been at least partially operational today. The current President Bush would therefore enjoy more options than those on today's unappealing menu - reliance on the severely constricted defenses we have today, endless negotiations, or the pre-emptive strike advocated by two former Clinton defense officials.

The most recent example of the dogged determination of congressional liberals to scuttle missile defense came last year. Two senior Democrats on the Armed Services Committee, Carl Levin (D.-Mich.) and Jack Reed (D.-R.I.), in what has become an annual ritual, tried to strip $50 million from the missile-defense budget for the deployment of ground-based interceptors and the construction of missile silos. Citing recent test failures, Reed dubbed the program a "rush to failure" and maintained that "the responsible thing to do is to slow down funding and reallocate the money." This cut-and-run strategy attracted 37 votes, including all but eight Democrats.

Sessions' wildly successful effort to boost both the testing and deployment sides of the missile-defense equation highlights yet another split among congressional Democrats on an important security issue. Missile-defense opponents will undoubtedly split hairs and argue that it is entirely consistent for them to have voted to slash the program before they voted to grow it. They will argue that their ire is focused on the operational side of missile defense, and that they support testing. But Sessions overtly sought to enhance both sides of the missile defense coin, with the only difference being the pressure generated by all the front-page coverage of the developing situation in North Korea.

Rather than pitting competing factions of Democrats against one another, as we saw during the recent congressional debates over Iraq, this divide pits individual Senate Democrats against themselves. It's amazing what a little focus can do.

Mike Franc, who has held a number of positions on Capitol Hill, is vice president of Government Relations at The Heritage Foundation.