Geopolitical risk is one of many uncertainties we accept as investors.

More often than not, it exists in the background: something to be mindful of but rarely a primary driver of market movements.

That dynamic changed at the end of February when the U.S. and Israel launched airstrikes in Iran, triggering a regional war the world and financial markets are still trying to understand.

Historically, wars are not as detrimental to stocks as you might expect. In 20 major military conflicts since World War II, the S&P 500 fell an average of just 6% from the start of the conflict to its lowest point. That’s according to a research paper published by RBC analyst Kelly Bogdanova. Those sell-offs also tend to be short-lived. In 19 of the 20 instances, the S&P fully recovered its losses in an average of four weeks.

Some of the more recent examples include Russia’s 2022 invasion of Ukraine (S&P -7.4%), the U.S. war on Iraq in 2003 (S&P -5.6%), and Iraq’s 1990 invasion of Kuwait (S&P -15.9%), which led to U.S. Operation Desert Storm.

International equities tend to be more vulnerable to new wars given, one, their geographic proximity to the conflict (compared to the U.S.), two, their economic reliance on oil/energy imports and, three, currency sell-offs that result from a “flight to the U.S. dollar” when conflicts arise.

We have seen this trend continue as it relates to Iran. In the first five trading days following airstrikes on Iran, the S&P 500 lost 2%. The Morningstar Europe Index fell more than 7%. And the MSCI Emerging Markets index declined 8.4%.

One obvious consequence of wars in the Middle East is disruption to global oil supplies. Roughly 20% of the world’s oil ships through the Strait of Hormuz along Iran’s southern border. Crude oil prices spiked more than 35% in the first week after airstrikes led to its effective closure.

The energy sector makes up only 3.4% of the S&P 500 by market capitalization, but more expensive oil will have downstream effects on global consumers. The longer this war lasts, the more severe the economic pain will be. Energy prices that remain elevated would re-stoke inflation for American families still struggling with a 26% cumulative increase in consumer prices since 2020.

Even though the stock market has generally proven resilient in times of war, there remains a risk this time could be different. The biggest outlier from the RBC analysis is the 1973 Yom Kippur War and Arab oil embargo. The S&P 500 dropped 16.1% in 42 days but didn’t recover those losses until six years later. Importantly, the event triggered a lengthy U.S. recession and an inflation surge, otherwise known as “stagflation.”

Stagflation would be the economic worst-case scenario. While unusual and unlikely, it is not outside the range of potential outcomes. The current war is already unusual in that it has spread far beyond Iran’s borders. Iran countered U.S.-Israeli attacks by firing missiles at 11 countries, most of which house U.S. military bases. Wars, by their nature, are unpredictable, and it’s fair to think of this war as being larger in both scope and complexity than previous Middle Eastern conflicts.

With or without wars, midterm election years tend to be more volatile for the stock market. In the 23 midterm years since 1934, the S&P 500 has averaged peak-to-trough declines of just more than 20%. That’s compared to average intra-year declines around 13% in non-midterm years.

Investors, in other words, should be mindful of the market’s historic resilience to wars but also expect more volatility in the months ahead.