The US president has doubled down on plans to impose 25% tariffs on EU goods.
During his first Cabinet meeting last night, Donald Trump said they would be brought in "on cars and all other things very soon".
EU leaders have been weighing up how they should respond.
Fine Gael MEP Seán Kelly says they must tread carefully.
“If he goes ahead with it, there will have to be a countermeasure from Europe and that will not be good for Europe, but won't be good for the United States either,” he said.
“So I think that will be Plan B but Plan A will be to try and use diplomatic measures in the meantime, maybe to discuss these battles and try to come to a more satisfactory arrangement.”
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British Prime Minister Keir Starmer has arrived in Washington after telling reporters a US security guarantee for Ukraine is essential to achieving peace.
Starmer has said he “trusts” Donald Trump - but has refused to say whether the US is “on our side”.
The US President last night claimed security guarantees for Ukraine against further Russian aggression would need to come from Europe, not America - if a deal's done to end the war.
The US president is also due to host Ukraine's leader tomorrow - to sign a minerals deal, which Mr Trump sees as compensation for military support.
“The previous administration put us in a very bad position, but we've been able to make a deal where we're going to get our money back and we're going to get a lot of money in the future, because we have taxpayers that shouldn't be footing the bill,” Trump said.
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Keir Starmer touched on these issues in the Commons, yesterday.
“The worst of all outcomes if there's to be a cessation of hostilities is that it is a short break, rather than sustained and lasting peace, and I think that that means there's got to be security guarantees,” he said.
The two men will meet at the White House later today.
Main image: President Donald Trump speaks to reporters in the Oval Office of the White House, where he signed an executive order, Thursday, Feb. 13, 2025, in Washington. (AP Photo/Ben Curtis)