Most Asian markets fell on Monday as fresh Chinese and US tariffs on goods worth hundreds of billions of dollars kicked in, though Donald Trump reiterated that the two sides were still due to hold talks this month.
Hong Kong was also weighed down by another weekend of violence, fuelling worries about possible Chinese intervention in the financial hub, while the unrest has also hit property firms and Macau's casinos.
Washington's latest levies on imports from China took effect on Sunday and were followed by Beijing's retaliation.
The measures are the latest in the long-running trade war between the world's top two economies, which has rattled markets and hit growth across the globe.
Still, Trump said negotiators would meet this month to discuss the issue. "We are talking to China, the meeting is still on," he told reporters.
However, analysts warned there was unlikely to be any end in the near term.
"After a rough August traders should buckle up for more volatility in September," said Neil Wilson, chief market analyst at Markets.com. "Trade and tariffs continue to gnaw away at investor confidence."
Tokyo and Sydney each ended 0.4% lower, while Singapore shed 0.8%, with Manila, Bangkok and Jakarta also down.
But Shanghai rose more than one percent after a better-than-expected reading on Chinese factory activity, though another index showed the sector remained in contraction and investors remain uncertain about the outlook as the trade war bites deeper. There were also gains in Seoul, Wellington and Taipei.
Violence grips Hong Kong
Hong Kong sank 0.8% after a weekend that saw some of the worst violence since protests began three months ago, with the airport targeted again, and demonstrators have called for a general strike on Monday though there was little sign that had been heeded.
The unrest has dragged a range of sectors, with tourist numbers tumbling, hitting casinos and hotel chains, while real estate shares are also being sold off.
"Markets are fretting on the increased likelihood of direct Chinese intervention and what that would mean for the future of one of Asia's leading financial centres," said Jeffrey Halley, senior market analyst for Asia-Pacific at OANDA.
"The answer is, not good, to put it bluntly. The economic impact will surely show in Hong Kong data going forward and may temper the mood of equity traders in Asia as the new month begins."
Oil prices extended Friday's steep losses owing to worries about the impact of the trade war on demand, while dealers were also concerned about reports that the Russian output cut last month fell short of an agreement with OPEC.
"A fissure is forming in OPEC+ compliance, which saw oil prices crater," said Stephen Innes, APAC Market Strategist at AxiTrader.
"On the surface, while it is not likely a significant divergence, it's the messaging that Russia is sending that spooks markets. While it could be little more than a tempest in an oil can at this stage, it's worth monitoring nonetheless."
Investors will be keeping an eye on markets in Argentina later in the day after the government imposed foreign-exchange controls on exporters following a week that saw a sharp drop in the peso.
In early trade London rose 0.3%, with traders bracing for a tough week in Westminster as Prime Minister Boris Johnson faces opposition from MPs across the political spectrum who have vowed legislation blocking a no-deal Brexit.
Also, EU negotiator Michel Barnier said the bloc will not change the divorce deal agreed with for PM Theresa May, fuelling expectations Britain will crash out with no agreement in place.
Paris and Frankfurt were both 0.1% higher.