Waltz’s fate was sealed by his inclusion of a journalist on a sensitive Signal group chat in March. But he had been clashing with other top officials since early in the administration, including over whether to pursue military action against Iran, senior officials and Trump advisers said Friday.

It wasn’t just Signalgate that led to Mike Waltz being canned as President Donald Trump‘s national security adviser. Before that scandal, Waltz had already angered Trump by going behind his back to talk with Israeli Prime Minister Benjamin Netanyahu about waging war on Iran,

President Donald Trump said Thursday that he would nominate outgoing national security adviser Mike Waltz to be the U.S. ambassador to the United Nations. Waltz, a former congressman from Florida, has been on shaky ground with Trump since March after he inadvertently added a journalist to a private chat on the messaging app Signal with other top national security officials to discuss military strikes in Yemen.