The reasons for China’s stock market troubles are many, but most analysts pointed to a move by the central bank to weaken China’s currency—the renminbi—as the primary cause for the decline. As my colleague Scott Cendrowski wrote Thursday, “China’s central bank lowered the yuan’s so-called reference rate, its trading peg to the U.S. dollar, by the largest margin since August, when the yuan dropped a couple percentage points over two days. That created a fear that China’s leaders are using a weaker currency to spark growth for an economy that is struggling more than expected.”

China’s management of its currency has been fascination for American observers for decades, as economists have long suspected that China undervalued its currency in order to subsidize its manufacturing and export industry. But those fears subsided in recent years, as the Chinese government allowed its currency to appreciate as part of a broader effort to rebalance its economy away from relying on investment and exports to one reliant more on domestic consumption.

But the sharp slowdown in the Chinese economy this year, paired with big losses in its equity markets, has thrown that analysis into question. And the fact that China’s currency is falling now is a sign that the transition the economy was supposed to be making towards the consumer is in trouble.

Earlier this year, China allowed its currency, the renminbi, to trade within a wider band around the value of the dollar, to which its value is pegged. But instead of rising in value, the renminbi fell against the dollar, and on Thursday the Chinese government allowed (or forced, depending on whom you ask) its currency to go down again, to its lowest value against the dollar in five years.

For some, this smacks of rank currency wars, with China fighting its quickly weakening economy with a cheaper currency to boost exports. Others argue that with the dollar stronger today than it has been in decades, it only makes sense to allow the yuan to weaken in response to this.

But wherever you come down on China’s motivations for its devaluation, it’s clear that a cheaper renminbi will send ripple effects through the global economy. And that’s likely why stocks in the U.S. and elsewhere plunged on Thursday.

The biggest fear is a deepening of a trade war that is being fought between the world’s economies over a very limited supply of global demand. One of China’s main competitors in the region, Vietnam, has moved three separate times this year to devalue its currency, with the last coming in August. “The policy action today is positive in its promptness in response to China’s devaluation,” Eugenia Fabon Victorino and Irene Cheung, analysts at Australia & New Zealand Banking Group Ltd., said in a research note at the time.

Meanwhile, other big exporters like Japan and Korea, have been watching the moves in the renminbi closely. Korea’s won hit a three year low earlier this year, while the Japanese central bank has been engaged in massive monetary stimulus in recent years. The Japanese government argues that this is purely to stimulate domestic demand, but economists like Robert Scott of the Economic Policy Institute have argued that Japan’s tactics are different than, for instance, the Federal Reserve’s quantitative easing, and that currency manipulation on the part of Japan has cost the U.S. hundreds of thousands of jobs per year.

As economist and China expert Michael Pettis has argued, what China’s troubles today underscore is the dearth of demand in the global economy. There are virtually no economies on earth today that are growing quickly as the result of rising incomes. Instead China’s rapid growth, until recently, has mostly been the product of a government policy that encourages excessive investment and keeps wages low in order to boost exports and employment. The few large economies that run trade deficits, though, like the United States and the U.K., don’t have the capacity to buy everything that China and the rest of the world’s exporters are trying to sell.

And therefore, it’s likely we’ll continue to see exporters fighting for every scrap of slow growing demand. Only time will tell whether China can ween itself off its dependency on exports. But what is certain is that the longer China waits to make the necessary reforms, the less stable the world’s second largest economy will be in the long run.