A fighter of the Islamic State of Iraq and the Levant (ISIL) holds an ISIL flag and a weapon on a street in the city of Mosul, June 23, 2014. REUTERS We were saddened last week to hear that at least 30 people were killed and many dozens more injured in ISIS-related suicide bombings that targeted an airport and train station in Brussels. The Belgian and European Union capital joins Paris, San Bernardino, Ankara, Jakarta and too many other cities in the past year alone that have come under fire from the Islamic terrorist group.

I was in Brussels most recently three years ago for an International Crisis Group meeting, and I was stunned by its beauty and elegance, highlighted with gold-trimmed architecture and vibrant flowers. In August, the city will celebrate the 20th anniversary of its Flower Carpet, which makes jaw-dropping use of over 600,000 begonias.

This artistry stands in stark contrast to the cowardice and brutality we saw last week.

While we can’t leave aside the immeasurable loss of life, tragic events such as these tend to have an enormous ripple effect on the economy. Between 70 and 80 percent of the European economy is based on consumption, and when people’s sense of safety and security ends up being rattled, they might temporarily avoid spending on travel and at malls, cinemas, restaurants and elsewhere.

I definitely saw this to be the case in the days following the 9/11 attacks. As I’ve shared with you before, I was in Manhattan at the time, attending a financial industry conference. Except for emergency services, all of New York City shut down in every way imaginable, from subways to airports to cell phones. (Because I had a San Antonio area code, I could still make calls on my phone.) I was lucky enough to reserve one of the last available rental cars in the area, and on the long drive home to Texas, I passed many stores and businesses that had closed for the week.

Indeed, few things are as disruptive to our lives and the economy as terrorist activity. A recent Gallup poll found that 79 percent of respondents believe global terrorism to be a “critical threat” to the U.S., the highest of any other potential threat.

What’s more, the economic impact of global terrorism has been rising steadily since 2010. In November, the Institute of Economics and Peace (IEP) calculated its cost at over $52 billion in 2014, the highest ever.

But this figure takes into account only direct, short-term costs. The 9/11 attacks were initially estimated to have cost $27.2 billion, but when you factor in indirect and long-term expenditures—the economic impact, war funding, future veterans’ care and more—it comes closer to $3.3 trillion, according to the New York Times.

So who are the beneficiaries in the aftermath of such disruptive events? Following the Paris attacks in November, aerospace and defense stocks such as Lockheed Martin, Boeing and Northrop Grumman got a boost.

Very often, governments use terrorist attacks to usurp individual rights and chip away at democracy. Little more than a month after 9/11, Congress passed the USA PATRIOT Act, which was vehemently criticized for violating people’s privacy.

Similarly, one of the biggest consequences of the Brussels attack might very well end up being political. Fueled by the Syrian migrant crisis, far-right parties and nationalist movements have already been gaining ground in Europe—the Alternative for Germany party, the National Front in France, the Danish People’s Party—and Brussels will likely serve as an impetus for further change.

The attacks also highlight the importance of owning gold, which investors have traditionally valued for its stability in times of crisis and currency fluctuations. Lately we’ve seen central banks all over the globe respond to lackluster growth with subzero rate polices, and this could accelerate if terrorist activity continues to shock our economies.

The yellow metal is currently up more than 15 percent since the beginning of 2016, making it one of the best performing assets of the year. Over the same time, inflows into gold ETFs have surged 20.3 percent. Earlier this month I shared with you an observation from Pierre Lassonde, cofounder of Franco-Nevada, who told me that for every $1 billion that goes into the SPDR Gold Trust (GLD), the price of gold rises approximately $30 per ounce.

I recommend a 10 percent weighting in gold—5 percent in gold stocks, the other 5 percent in physical bars, coins and jewelry—in both good times and bad.