China’s export growth unexpectedly slowed in September, curbing a trade rebound that has been a bright spot for a weakening economy that policymakers are relying on manufacturing to power. Exports climbed just 2.4% in dollar terms from a year earlier to almost $304 billion, the lowest level since May, the customs administration said Monday. Shipments to key markets including Japan, South Korea and Taiwan all fell, while exports to the European Union and the US marked their slowest rise in at least four months as politicians ramped up tariffs.

Russian purchases of Chinese goods soared to a record $11 billion, as Beijing continues to shield Moscow from economic isolation after Western companies producing everything from cars to phones quit President Vladimir Putin’s nation due to sanctions to punish his military aggression.

“China’s export growth has been remarkably strong this year and helped to offset the weak domestic demand,” said Zhiwei Zhang, president and chief economist at Pinpoint Asset Management. “Looking ahead, it would be difficult to sustain strong export growth into next year, as trade tension heightens.”

Chinese exports have powered the economy this year with shipments through September soaring to the second highest value on record. Weak consumer spending at home, however, has dampened the appetite for foreign products spurring a record trade surplus, and prompting US President Joe Biden and others to impose trade curbs.

Exemplifying that problem, imports inched up just 0.3%, leaving a trade surplus of almost $82 billion for September and $690 billion for the first nine months of this year.