China’s trade surplus with the United States widened to a record in August even as the country’s export growth slowed slightly, an outcome that could push President Donald Trump to turn up the heat on Beijing in their cantankerous trade dispute.

The politically sensitive surplus hit $31.05 billion in August, up from $28.09 billion in July and surpassing the previous record set in June.

Over the first eight months of the year, China’s surplus with its largest export market has risen nearly 15 percent, adding to tensions in the trade relationship between the world’s two largest economies.

China’s annual export growth in August moderated slightly to 9.8 percent, customs data showed on Saturday, the weakest rate since March but only slightly below recent trends.

The number missed analysts’ forecasts that shipments from the world’s largest exporter would rise 10.1 percent, slowing only slightly from 12.2 percent in July.

The world’s largest trading nation got off to a strong start this year, but its economic outlook is being clouded by the rapidly escalating U.S. trade dispute and cooling domestic demand.

Investors fear Washington could impose duties on another $200 billion of Chinese imports at any time, in what would be its most sweeping measures yet, and Beijing has vowed to once again retaliate.

Trump upped the ante again on Friday as he warned he was ready to slap tariffs on nearly all Chinese imports to the United States, threatening duties on another $267 billion of goods on top of $200 billion in imports primed for levies in coming days.