President Donald Trump said Tuesday that Iran will pay a heavy price for any attack on the American embassy in Baghdad amid protests against U.S. airstrikes in Iraq over the weekend.

In a pair of tweets, Trump said the diplomatic compound is safe and additional forces had arrived on the scene. He also thanked the Iraqi leadership for their response to the demonstrations.

“Iran will be held fully responsible for lives lost, or damage incurred, at any of our facilities. They will pay a very BIG PRICE! This is not a Warning, it is a Threat,” he wrote.

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