WASHINGTON (Reuters) - US President Donald Trump said yesterday whether he would strike Iran in response to the downing of an American aircraft over the Strait of Hormuz by saying: "You will know soon."

"Iran has made a big mistake and the US military has been in the international airspace, and we have documented it," he said.

A senior US official said the United States should send a strong message to its Gulf allies in the face of Iranian threats.

For his part, Air Force Commander in the Central American Command, Joseph Gustella, said that the Iranian Revolutionary Guard dropped the American aircraft with a missile over international waters and not over Iranian airspace, in violation of the allegations made by Tehran about the violation of Iranian airspace.

Fox News quoted an unnamed US official as saying the Pentagon had set a map of Iranian targets but was waiting for a decision from the White House.

President Trump and senior military commanders and advisers held a meeting at the White House to discuss ways to respond to the downing of the US aircraft.