These days, with interest rates going up and down, more and more people seem to be looking for safe places to invest. I also reorganized my portfolio and started looking into U.S. bonds, but it turned out to be more complicated than I expected—especially for Korean investors, since you have to take exchange-rate issues into account as well.

To start with the basics of bonds, think of them as a kind of IOU issued when a government or company borrows money. Investors receive a set interest payment and get their principal back at maturity. There are three main types of U.S. government bonds: T-bills with maturities under 1 year, T-notes with 1 to 10 years, and T-bonds with 10 to 30 years. As a general rule, the longer the maturity, the higher the interest rate, but if the economy is doing poorly, demand for long-term bonds can surge—creating the opposite effect where short-term bond rates become higher.

When thinking about how to buy U.S. bonds, the first thing to consider is the relationship between interest rates and yield. Bond prices and interest rates move in opposite directions. When interest rates rise, newly issued bonds offer higher rates, so the price of existing bonds falls. Conversely, when interest rates fall, the price of existing bonds rises. In the end, yield reflects investors’ sentiment.

The advantages of investing in U.S. government bonds are fairly clear. First, since the U.S. government guarantees repayment, the safety level is the highest. That’s also why many investors flock to them during economic recessions. Second, because fixed interest rates apply, you can expect predictable returns. This makes them ideal for retirees or anyone who needs stable cash flow. Third, the bond market is so large and active that liquidity is good—you can sell quickly when you need to. Fourth, although interest from U.S. government bonds is subject to federal tax, state and local taxes are exempt, so your after-tax return is quite attractive.

Of course, there are risks. If interest rates rise, the value of existing bonds declines—so if you need to sell before maturity, you could take a loss. Inflation is also a problem: because the interest rate is fixed, if prices rise, your real return falls. Using TIPS (Treasury Inflation-Protected Securities) can solve this to some extent. From the perspective of foreign investors, exchange-rate risk also can’t be ignored.

There are three main ways to buy U.S. bonds. The first is buying directly. By purchasing directly from the U.S. government through the TreasuryDirect website, there are no management fees, and you can receive interest payments regularly until maturity. However, individuals can only buy up to $10,000. To diversify, you’d need to buy multiple bonds, which can be cumbersome to manage. And if you have to sell before maturity, you might need to sell at a discounted price.

The second is to use bond funds. Professional fund managers manage a mix of multiple bonds, so the risk of any individual bond is spread out. You can invest in a diversified portfolio with a relatively small amount of money. The downside is that management fees apply, so your overall return is reduced.

The third is to buy bond ETFs. Because they track an index, their fees are lower than those of funds, and you can trade them on an exchange like stocks, which means liquidity is also good. However, since you’re exposed to market volatility as-is, even if the underlying bonds are stable, the ETF price can still fluctuate. Also, because they are passive funds, they don’t benefit from active management by a fund manager.

For Korean investors, it’s generally a good idea to build a portfolio that mixes Korean government bonds and U.S. government bonds. Holding bonds from different countries provides geographic diversification, and because you hold both Korean won and U.S. dollars, you can hedge exchange-rate fluctuation risk to some degree. Since the economic cycles of Korea and the U.S. don’t always align, when one side is weak, the other can help support the portfolio.

There are also ways to manage exchange-rate risk. You can use derivatives like forward contracts to lock in the exchange rate. This reduces currency risk, but it also means you miss out on opportunities from favorable exchange-rate movements. So some people hedge only part of their investment and keep the rest exposed. When the U.S. dollar is strong, the unhedged portion may generate better returns; when it’s weak, the hedged portion helps prevent losses.

Duration is also an important concept. It measures a bond’s sensitivity to changes in interest rates. If your goal is principal preservation, you would generally move toward longer-maturity bonds; if you want to reduce interest-rate risk, you can adjust your mix by including more shorter-maturity bonds.

You also need to check taxes carefully. Interest from U.S. government bonds is subject to U.S. federal tax, but it may also be taxed in Korea. Fortunately, Korea and the U.S. have a double taxation agreement (DTA) in place, so the same income isn’t taxed twice. Still, it’s a good idea to consult a tax professional to confirm the details accurately.

In practice, by creating a balanced portfolio with 50% Korean government bonds and 50% U.S. government bonds, you can achieve both principal protection and income generation at the same time. Because your dependency on the economy of any one country decreases, overall risk is reduced. When the U.S. dollar is strong, the unhedged portion of U.S. government bonds can provide returns; when it’s weak, the hedged portion can offset losses—so balance is maintained automatically.

In conclusion, the way to buy U.S. bonds depends on your investment goals, your ability to tolerate risk, and how much time you have. If you want conservative, long-term investing, direct purchase is suitable; if you want diversification and professional management, bond funds are better; and if you want low fees and flexibility, ETFs are a good choice. No matter which method you choose, it’s important to properly understand and invest while accounting for risk factors such as interest rates, inflation, and exchange rates. Especially for Korean investors, if you mix U.S. government bonds and Korean government bonds appropriately in your portfolio, you can expect more stable returns.