America’s bombers have long served as a potent representation of the nation’s economic and engineering prowess. From unleashing massive amounts of ordnance across Europe in B-52s to delivering extremely accurate weapons platforms from stealth bombers the enemy never even knew was there, the ability to blow something up somewhere else in the world has long been among America’s greatest military strengths. However, as repeated missile-based offensives in Syria have demonstrated, the United States no longer needs to put a manned aircraft in harm’s way to destroy far off targets — and as America’s hypersonic missile platforms come to fruition, they may have a higher success rate than even the nation’s stealthiest bombers.

The missile versus bomber debate isn’t a new one. Ever since mankind developed the technology to fire missiles from great distances with a high degree of accuracy, some have contended that this capability removes the need for aircraft employed specifically for the delivery of ordnance behind enemy lines. To be clear, there are sound arguments to be made from either side of this conflict. Included are concerns about maintaining adequate stockpiles of missiles to offer the same degree of deterrence allowed by bombers, a constant shifting back and forth between which methodology is more cost effective in the present day, and of course, our cultural inclinations to both maintain the status quo and push the boundaries of our own technological capabilities.

In 2010, Thomas Hamilton of the Rand Corporation prepared a report for the U.S. Air Force outlining many of the most potent arguments in favor of deep penetration bombers over the use of “expendable missiles” in a large-scale conflict. By using life-cycle cost estimates that included procurement and operation of a new deep penetration bomber (which, at this point, we know will be the B-21 Raider), Hamilton was able to extrapolate the cost of delivering a similar amount of ordnance via cruise missiles at standoff distances. What Hamilton found was that missiles do indeed offer a cost savings over bombers in short duration offensives like the retaliatory strikes seemingly favored by the Trump administration. However, using 12 cruise missiles launched per day as an average, Hamilton’s findings showed that once a conflict extends beyond the thirty-day mark, bombers once again emerge as the most cost-effective means of ordnance delivery.

Hamilton also pointed out that nations with an awareness of America’s missile stockpile could calculate an estimated inventory and use that figure to inform their strategy; intentionally trying to exhaust the ready supply of missiles before launching new offensives against a weakened American defense apparatus. Bombers, on the other hand, can potentially carry a multitude of different weapons platforms.

These assertions represent the common mindset among defense officials to this day — as bomber and missile technology has, for the most part, improved at a consistent rate for decades. However, strong as Hamilton’s arguments were at the time, they may not stand up to the advent of hypersonic missile technology.

These platforms travel at speeds in excess of Mach 5, making an intercept of the sort often touted by both American and Russian militaries all but impossible with current technology. With an accurate targeting apparatus and a missile that has proven reliable, a single hypersonic missile could do the job of ten Tomahawk cruise missiles of the sort the United States recently used in Syria. Subsonic Tomahawks are extremely capable platforms, but nations like Russia and China have developed defenses with that missile specifically in mind. That means it takes more missiles to overwhelm potential defenses and ensure the destruction of the target. With an indefensible missile, however — one is enough.

To date, bombers remain the most viable economic method of delivering nuclear or conventional payloads over the span of a legitimately large-scale conflict, though missiles offer a better alternative for today’s commonly preferred strikes. As such, continued investment in both seems prudent… but in the decades to come, as hypersonic technology becomes more cost-effective, the decision may ultimately come down to one thing: whether or not a means of defending against these new missiles can be developed and implemented.

If not, the days of stealth bombers may be numbered.