During this holiday season, Americans gather with friends and family to count our blessings. Blessed to live in the land of the free and home of the brave, we give thanks to the courageous sons and daughters who put their lives on the line to secure freedom and liberty from one generation to the next.

The federal government’s number one priority is national security. That’s why Congress takes care to adequately fund the Department of Defense (DoD) to maintain military readiness and ensure our men and women in uniform have what’s needed to do their jobs. However, that doesn’t give lawmakers license to put the Pentagon budget on autopilot. To the contrary, it’s the constitutional responsibility of each and every lawmaker to conduct oversight.

As a Pentagon watchdog, I’ve locked horns with plenty of top brass, inspectors general, and government contractors over the span of four decades. In so doing, I’ve used every tool in my lawmaker’s arsenal to bring fiscal integrity to an enormous, unaccountable defense budget. The road to fiscal integrity has included countless letters, investigations, congressional hearings, legislative holds, spending reforms, and whistleblower protections to hold the DoD accountable. Along the way, some folks likely considered this farm state senator a nuisance for sticking my nose into the Pentagon’s spending trough. I say hogwash.

Taxpayers have every right to expect the Pentagon to account for every penny. In the last fiscal year, Congress authorized more than $700 billion for the Defense Department. That’s why I’m disgusted the Pentagon once again flunked its most recent audit. Let’s not forget, the DoD Inspector General (DoD IG) completed the Pentagon’s very first full financial audit just last year. That came 28 years after Congress enacted a law requiring every federal agency to conduct, and pass, an annual audit.

Last week, the bean counters at the DoD reported their findings for fiscal year 2019. The OIG deployed 1,400 auditors to 600 sites around the world. They surveyed $2.9 trillion in assets and tallied $2.8 trillion liabilities. Nevertheless, after spending $1 billion to conduct the audit, the DoD IG was unable to issue a clean opinion.

What did it find? The DoD would have you believe it demonstrated progress. The Defense Commissary Agency earned a clean opinion for the first time. No significant issues were found with payment accounts made to service members or DoD employees. True, more than 550 notices of findings and recommendations from the last audit were closed. However, the auditors reissued 1,800 of fiscal year 2018 recommendations and flagged 1,300 new ones for fiscal year 2019. The bottom line is clear. Material weaknesses, significant deficiencies and financial mismanagement processes are still standard operating procedure for the Pentagon.

That’s why I’m as concerned as ever. Lack of accountability means the left hand doesn’t know what the right hand is doing. It means the barn door is wide open for waste, fraud, and abuse. Without supporting documentation allowing DoD to track where the money goes, the billion-dollar audit won’t amount to a hill of beans if things aren’t cleaned up from one year to the next.

Systemic IT flaws continue to muddy inventory accounts and prohibit auditors from accurately assessing just how bad the Pentagon’s books are. When data from financial systems are unreliable, it’s impossible to know where the money is spent. Don’t forget, the DoD spends billions each year on its outdated and unreliable IT and financial management systems, with no concrete plan to migrate and update the systems. Although the DoD IG found the Pentagon had solved about 30 percent of the identified IT recommendations from last year’s audit, 70 percent remain unresolved. This is how a molehill grows into a mountain.

Unsupported adjustments, unsupported transactions, and unsupported spending add up to one thing: Unsupported assurances on how taxpayer money is spent. The acting inspector general says the audit shows progress, but I say a whole lot more progress is necessary.

Already, the DoD is preparing to undertake another full financial audit for fiscal year 2020. I’m afraid it will be another billion dollar effort that will produce another failed audit.

It’s as important as ever to continue the march to fiscal accountability. As long as I’m in the U.S. Senate, I’ll continue to talk turkey about Pentagon spending. It’s in our national interest to prevent defense dollars from getting gobbled up by waste, fraud and abuse.

Chuck Grassley has represented Iowa as a Republican in the U.S. Senate since 1981.

The views and opinions expressed in this commentary are those of the author and do not reflect the official position of The Daily Caller.