The more Americans hear about growing security threats worldwide, the more grateful they must feel to have a world-class military. But few know the disturbing truth: Our military, quite frankly, is in a death spiral.

It's too small for its workload, underfunded to repair and replace equipment that is rapidly wearing out, and ill-served by obsolescent infrastructure at its ports, bases, and airfields. And it's increasingly unprepared for the rigors of a major conventional conflict, the likes of which have cropped up every 20 years or so with alarming regularity since the Civil War.

Gen. Daniel B. Allyn, until recently the vice chief of staff of the Army, testified that only "one-third of our BCTs (brigade combat teams), one-fourth of our combat aviation brigades, and half of our division headquarters" are considered ready. Of the Army's 31 BCTs, only three are available to immediately deploy to a conflict.

The pace of decline has been precipitous. As recently as 2012, there were 45 BCTs, and nearly the entire Army was involved in the rotational base supporting combat operations in Afghanistan and Iraq.

The U.S. Air Force is 24 percent short of the fighters it needs and is short 1,000 pilots and more than 3,000 "maintainers" who keep its aircraft running. Only four of its 32 combat-coded squadrons are ready to execute all wartime missions. Prior to 1991, the Air Force purchased more than 500 aircraft a year to replace the aging ones it was purging from its inventory; since then, it has averaged fewer than 100 purchases per year.

The Marine Corps "is insufficiently manned, trained and equipped across the depth of the force to operate in an ever-evolving operational environment," according to Gen. Glenn Walters, assistant commandant of the Marine Corps. Only 41 percent of the Corps' aviation platforms are considered flyable.

At only 276 combatants, the Navy has two-thirds the ships it did near the end of the Cold War. It now has the smallest battle fleet since before World War I. Of its 18 classes of ships, only seven are currently in production. The recent spate of ship collisions and a grounding imply problems in basic ship-handling skills.

And what of those security threats?

China is now spending more than six times as much on defense as it was in the early 1990s. It's rapidly building a blue-water navy and is fielding a fifth-generation stealth fighter to compete with America's F-22.

Russia continues to occupy Ukraine and actively support separatist rebels carving out territory in the southeast of the country. It has salvaged the tyrannical regime of Bashar Assad in Syria and it actively threatens NATO members in the north of Europe.

North Korea, meanwhile, has become a nuclear power and is close to realizing its goal of possessing missiles capable of delivering nuclear warheads to any spot on the planet. Iran is supporting terrorist groups such as Hezbollah. An assortment of odious terror groups continues to ravage portions of the Middle East and Africa.

Yet, like France and Britain in the 1930s, the United States has neglected to keep its military strong enough to confront regimes threatening the peace and security of the free world. Winston Churchill repeatedly warned his fellow citizens of the dangers of complacency, misguided priorities and weakness of will. He urged them to take timely action when dangers threatened. They didn't listen, and World War II soon followed.

A similar state of affairs afflicts the United States today. Yet Congress consistently prefers to focus almost solely on domestic issues, pushing to increase spending on everything from health care and education to subsidized crop insurance and alternative energy options. But these have increasingly come at the cost of providing for the nation's defense, arguably the pre-eminent responsibility and obligation of the federal government.

The United States stands at a crossroads. We can't keep underfunding our defense and expect to be able to maintain our security and economic interests, let alone continue to lead the free world as the pre-eminent global power. Time is running short.