The world’s richest nations should work together to address trade imbalances that may be undermining the resilience of the global economy and straining relations, the International Monetary Fund said.

Countries with excessive current-account surpluses, such as Germany and South Korea, should use fiscal policy to boost investment or domestic demand, the IMF said in an update on the global economy ahead of Group of 20 meetings this week in Hamburg. Meanwhile, nations like the U.S. and U.K. with excessive deficits should tighten their fiscal belts, according to the Washington-based fund.

“Both surplus and deficit countries should confront this problem now to avoid larger corrections down the road,” IMF Managing Director Christine Lagarde said in a blog post accompanying the report. The G-20 summit is also “a chance to strengthen the global trading system and reaffirm our commitment to well-enforced rules that promote competition while creating a level playing field,” she said.

The meetings this week will be a test of the global economic-policy consensus at a time when the world’s largest economy is led by President Donald Trump, who’s attending his first G-20 summit. In the run-up to the leaders’ forum, U.S. officials sought to water down G-20 pledges to avoid protectionism.

The global recovery remains on track, though the growth engines have shifted, the IMF said, noting that the U.S. economy went through a “soft patch” early in the year and many European and Asian countries expanded faster than expected.

However, the fund warned that imbalances remain and vulnerabilities are rising. China’s robust growth is being “fueled in part by rapid credit and fiscal expansion that aggravates financial vulnerabilities.” Meanwhile, corporate leverage is high in some emerging markets and balance sheets are fragile, the IMF said.

“Yes, we have momentum. But we cannot rest easy -- both old and new risks threaten our goal of creating higher growth that is shared by all,” Lagarde said.