A Democratic-controlled Congress could use its spending powers to restrict President Donald Trump’s ability to wage war in the Middle East, but would face greater difficulty reversing his tariffs, a former US ambassador to Vietnam has said.
Ted Osius made the assessment as Americans voted in the midterm elections, speaking at a business summit in Ho Chi Minh City. He said the outcome could have significant consequences for the Iran war and the global economy.
“The Iran war is extremely unpopular in the United States, and it’s one of the factors that will be decisive in this election,” said Mr Osius, who served as ambassador to Vietnam from 2014 to 2017.
“I expect that Congress would use the power of the purse to curb the president’s ability to wage war in the Middle East,” he added.
About 65% of Americans disapproved of Mr Trump’s handling of US military action in Iran in a Pew Research Centre survey released on October 8. Disapproval stood at 61% in a March survey, according to the polling organisation.
Most polling averages placed the Democrats ahead of the Republicans on the generic ballot before the vote. Several independent forecasts suggested the Democrats could regain control of the House of Representatives, while the Senate was considered more uncertain.
Tariffs harder for Congress to reverse
Mr Osius said a Democratic victory could bring pressure for a more predictable trade policy, but warned that tariffs would be more difficult to dismantle because the authority to impose them rested largely with the executive.
“I don’t think we’ll suddenly go back to the status quo ante,” he said. “Unfortunately, it’s actually harder to unwind tariffs once you put them in place.”
Vietnam was among the countries in south-east Asia hardest hit by Mr Trump’s initial tariffs in April 2025, receiving a 46% rate before it was reduced to 20% under a deal. Governments across the region have since negotiated with Washington, offering to lower their own trade barriers and buy more US goods.
After a Supreme Court ruling on February 20 found that tariffs imposed under the International Emergency Economic Powers Act, including the so-called Liberation Day levies, were unlawful, the administration turned to other justifications. These included wider duties introduced following allegations of forced labour and overcapacity.
Mr Osius said an electoral setback could demonstrate the limits of a more coercive approach to foreign policy.
“When you sort of run a state like a mobster, it may work in the short term, but in the long term it doesn’t,” he said. “It’s much more effective, especially in this part of the world, to have predictable policies, and to show that rule of law and rules-driven trade works to everyone’s benefit.”
Despite the tariffs, Vietnam’s economy grew by almost 10% in the third quarter of 2026, following growth of 8.2% and 8.8% in the first and second quarters. The Asian Development Bank expects developing south-east Asia to grow by 4.7% this year and 4.9% in 2027.
Jens Lottner, chief executive of Vietnamese bank Techcombank, said exports had risen by 30% year on year despite a current 12.5% tariff on Vietnamese exports to the US.
“If you’re a bank, you’re a proxy on the economy,” he said. “We still have a couple of very good years ahead of us.”
Amol Gupte, Citi’s head for South Asia, said tariffs were changing the direction of global commerce rather than reducing its overall volume. Exports from China to the US had fallen sharply, he said, but China’s total exports had continued to grow substantially.
The summit also heard warnings that south-east Asia remained exposed to wider geopolitical tensions. Lynn Kuok, the Lee Kuan Yew Chair in Southeast Asia Studies at the Brookings Institution, said China had increased its presence off Vietnam’s coast and restarted the rebuilding of islands there after a decade-long pause.
She also identified the Strait of Malacca, between Malaysia and Indonesia, as a potential vulnerability after the blockage of the Strait of Hormuz. Malaysia, Indonesia and Singapore have pledged to keep the passage open, but Ms Kuok warned that a future nationalist government could seek to close it or face pressure from other powers to do so.
Ms Kuok said members of the Association of Southeast Asian Nations were relying on international law to defend their interests without choosing between Washington and Beijing.
“They’re not choosing U.S. or China; they’re choosing principles of international law,” she said.
