President Donald Trump‘s decision to launch a missile strike against Syria following a deadly chemical attack in the northwestern part of the country was influenced by his “heartbroken and outraged” daughter Ivanka, according to one of her brothers.

In an interview with The Daily Telegraph, Eric Trump said Ivanka likely swayed their father. “Ivanka is the mother of three kids and she has influence,” he said. “I’m sure she said, ‘Listen, this is horrible stuff.’ My father will act in times like that.”

Trump said his father would not be intimidated by Russia threatening military escalation in Syria after the strike.

“There will be no one harder — he has more backbone than anybody,” Eric Trump said. “He is not a guy who gets intimidated. I can tell you he is tough and won’t be pushed around. The cards will shake out the way they do but he’s tough.”

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Write to Mahita Gajanan at mahita.gajanan@time.com.