Malaysian Foreign Minister Mohamad Hasan's call for a united front came in his opening speech at a meeting of foreign ministers from the Association of Southeast Asian Nations (ASEAN) in Kuala Lumpur on Sunday.
He also reiterated the bloc's call to warring parties in Myanmar to end hostilities in a deadly civil war that has killed thousands and displaced millions of people since a 2021 government takeover by the military.
"ASEAN nations are among those most heavily affected by the US-imposed tariffs," he said.
The US–China trade war is dramatically disrupting production and trade patterns worldwide.
"A global economic slowdown is likely to happen," Mohamad said.
"We must seize this moment to deepen regional economic integration, so that we can better shield our region from external shocks."
ASEAN countries, many of which rely on exports to the US, are reeling from tariffs imposed by the Trump administration ranging from 10 per cent to 49 per cent.
Six of the association's 10 member nations were among the worst-hit with tariffs ranging from 32 per cent to 49 per cent.
ASEAN unsuccessfully sought an initial meeting with the US as a bloc. When US President Donald Trump last month announced a 90-day pause on the tariffs, countries including Malaysia, Indonesia, Thailand and Vietnam swiftly began trade negotiations with Washington.
The meeting of foreign ministers preceded a planned ASEAN leaders' summit Monday in Malaysia, the bloc's current chair.
A summit is expected to follow on Tuesday with Chinese Premier Li Qiang and leaders from the Gulf Co-operation Council comprising Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates.
ASEAN's unity is crucial as the region grapples with impacts of climate change and disruption from the malevolent use of artificial intelligence and other unregulated technologies, Mohamad said, adding that ASEAN's centrality will be tested by external pressure, including a superpower rivalry.
"External pressures are rising, and the scope of challenges has never had higher stakes," he said.
"It is therefore crucial that we reinforce the ties that bind us, so as to not unravel under external pressures. For ASEAN, unity is now more important than ever."
ASEAN remained committed to help war-torn Myanmar, which is recovering from a March earthquake that killed more than 3700 people, Mohamad said.
Myanmar's military leaders were barred from attending ASEAN meetings after refusing to comply with ASEAN's peace plan, which includes negotiations and delivery of humanitarian aid.
