US President Donald Trump said early on Tuesday that Iran was "orchestrating" an attack on the U.S. embassy in Iraq and will be held responsible for it.

"Iran killed an American contractor, wounding many. We strongly responded, and always will. Now Iran is orchestrating an attack on the U.S. Embassy in Iraq. They will be held fully responsible. In addition, we expect Iraq to use its forces to protect the Embassy, and so notified", he said in a tweet.