The U.S. government was robbed.

Last month, hackers stole $100 million from the Federal Reserve. Authorities recovered $19 million, and the hackers got away with $81 million.

It was the largest bank robbery in history.

Nick Giambruno, editor of International Man, explains what happened.

Last month, an international group of hackers robbed Bangladesh's account at the Federal Reserve, the central bank of the U.S.

First, the hackers used a computer virus to break into the security system of Bangladesh's central bank. Then they stole the usernames and passwords the bank uses for payment transfers. The hackers used this information to wire over $100 million from Bangladesh's Federal Reserve account to the Philippines and Sri Lanka. From there, they funneled it to casinos and withdrew it as cash.

Big as this bank robbery was, it was only the latest major cyberattack against the United States. It won't be the last, either.

• We've been warning readers about this threat for months...

In December, we explained why a cyberattack is the biggest threat to your wealth. Although few people realize it, a hacker could instantly wipe out your life savings.

To grasp why this threat is so serious, think about the "money" in your bank account. What is it really?

These days, it's certainly not a claim to gold or another hard asset.

And it's not cash. Many local banks keep less than $100,000 in cash on hand. That's not nearly enough to cover everyone's deposits.

The truth is, the money in your bank account is just digital bytes in a computer. It's backed by nothing but confidence in the banking system. Most people assume this is good enough. They think, "Surely, the financial system is completely safe."

• The U.S. financial system is far more vulnerable than you think...

Last year, we learned of a massive cyberattack against JPMorgan Chase, E*Trade, and Scottrade.

These are some of the world's largest and most sophisticated financial institutions. Americans trust them to safeguard hundreds of billions of dollars. Yet hackers were able to steal the personal data of more than 100 million customers from them.

• The government can't defend itself against hackers, either...

The Department of Defense, CIA, and IRS have all been hacked.

Last year, hackers broke into President Obama's email. They accessed the president's personal schedule and private conversations with foreign officials. U.S. officials think the Russian government was behind the attack.

There were more than 77,000 "cyber-incidents" against the U.S. government last year, according to Reuters. That's more than 200 per day, and a 10% increase over 2014.

Still, millions of Americans assume the government will protect their bank account from a cyberattack. Don't be one of these people. The government can't even protect itself.

• There are no red flags before a cyberattack...

They just happen. And they're usually over before the victim knows he's been hit.

If you aren't prepared ahead of time, you're completely helpless. All the money you've earned, all the hard work, the sweat, the sacrifice, the nest egg you've built to provide for your family...

It could all vanish in an instant.

The good news is there are practical steps you can take to protect yourself.

• We recommend moving some money outside of the digital financial system...

This means holding enough cash for you and your family to live on for up to six months. You might store it in a safe or public storage unit. You could even bury it in a waterproof container in your backyard.

This might seem like crazy advice. However, if you're like most people, almost all of your money is in highly vulnerable bank and brokerage accounts. Remember, that money is just bits and bytes in a computer. A skilled hacker could make it disappear in an instant.