After US President Donald Trump once again threatened new tariffs late last week - this time on the EU - Aussie shares are set for a flat open to start the week.

ASX 200 futures are showing little movement after former US President Donald Trump raised the spectre of 50% tariffs on the European Union.

If carried through, it would see the EU slugged with a tariff higher than the 39% Trump announced from the podium at his "Liberation Day" event in early-April.

EU bigwigs are standing their ground, however, with Maros Sefcovic, the EU's Commissioner for Trade and Economic Security, said that he's "ready to defend [Europe's] interests" and that threats aren't the way to move the conversation forward.

Spoke w @jamiesongreer & @howardlutnick. The EU's fully engaged, committed to securing a deal that works for both. @EU_Commission remains ready to work in good faith. EU-US trade is unmatched & must be guided by mutual respect, not threats. We stand ready to defend our interests. pic.twitter.com/RfIo5K4aus

— Maroš Šefčovič🇪🇺 (@MarosSefcovic) May 23, 2025

The comments, made late last week, rattled global markets and are now reverberating across Asia-Pacific trading desks. The S&P 500 closed down two-thirds of a percent following the news during their Friday session.

At 7:30am AEST, SPI 200 futures were barely changed, pointing to a muted open for the local market. The market risks trending lower following the latest Trump tirade as investors once again weigh geopolitical exposure.

Volatility expectations remain contained. The ASX 200 VIX, a measure of expected 30-day volatility in the index, fell close to 3% in early Monday trade, signalling that while investors are jittery, there is no immediate panic. Still, the tone is cautious heading into the new week.

Trump’s tariff threat adds a new layer of uncertainty to a market already juggling the implications of sticky inflation data and central bank policy recalibrations. While the President’s comments are not yet policy, the former has a habit of turning quickly into the latter.

With futures flat and volatility indicators subdued, Monday’s session is unlikely to deliver fireworks. But beneath the surface, sentiment is shifting—and the path of least resistance may be down.