Market uncertainty tied to the ongoing US-China trade war has spurred more transactions than ever before between the American dollar and the Chinese yuan in recent months.

Much of that volume comes as businesses and investors with exposure to the Chinese market are looking to hedge their foreign exchange risk.

Many of them are looking to buy into the strengthening dollar, and that’s stoked speculation that Chinese authorities are intervening in the market to defend their currency, boosting trading volumes to new highs in the process, CNBC reported.

On Tuesday, major state-owned banks were selling dollars to defend the Chinese yuan, as the greenback climbed to a 16-month peak against a basket for currencies.

Most trading between the two currencies takes place on the spot market, where dollars and yuan change hands as soon as a deal is done. That sort of market has seen volumes surge this year for the currency pair.

But futures trading—where the transaction is agreed to take place at a later date at a certain price—is also increasingly catching dollar-yuan traders’ interests, according to Benjamin Lu, an investment analyst with Singapore brokerage Phillip Futures.

Lu cited commodity traders as some of those who are concerned about exposure to the US-China tariff battle and are consequently looking for various ways to hedge the risk.

Proprietary traders also see opportunities for arbitrage between different products as the yuan faces volatility against the dollar, he added.

Within China’s mainland borders, the yuan’s price against other currencies is tightly controlled by the People’s Bank of China, while the so-called offshore yuan represents the currency’s value in markets beyond Beijing’s control.

Both measures of the yuan have declined against the dollar recently as China’s economy faces headwinds from Beijing’s trade war with Washington, and as the greenback strengthens on the back of robust US growth.

So far in 2018, the dollar has risen about 7% against the onshore Chinese yuan.

Against that backdrop, the Hong Kong Exchange and the Singapore Exchange—two main centers for dollar-yuan currency futures—have both reported record trading volumes in the dollar-offshore yuan pair this year.