'WORLD War 3' has been trending on Twitter after the shock US assassination of Iran's top general, Qasem Soleimani, this morning in Baghdad.
Experts and leaders across the spectrum have been left stunned and uncertain of the future in the wake of Trump's shock move.
People are expressing serious concern around the world that the move will cause the outbreak of World War III as Iran's supreme leader Ali Khamenei promised 'harsh vengeance', 'jihad' and 'crushing revenge' as news of the assassination broke.
Searches for ‘World War 3’ also spiked on Google within hours of the airstrike in Iraq overnight.
Google Trends recorded ‘Iran’ as the second most searched term in the United States, with more than 500,000 searches for the topic.
This week, Mr Trump blamed Iran for a protest in Iraq which saw demonstrators break into the US embassy in Baghdad and torched the place.
WORLD WAR III
In a tweet, Iran’s leader Ayatollah Khomeinei said the ‘criminals’ responsible had ‘his [Soleimani] and other martyrs’ blood on their evil hands’. He added: ‘God willing, his work and his path will not be stopped.’
The dramatic attack came months of tensions between the US and Iran in which Tehran shot down an American military surveillance drone and seized oil tankers.
Experts told the BBC's Today programme that the Iranian reaction has been "extraordinary" and there are high-level talks of "very severe revenge" with "consequences unknown".
Other experts called the assassination 'a powerful political weapon' against the US but all agree that escalation and retaliation is to be expected.
Trump himself tweeted a picture of an American flag after the attack was announced, and then tweeted "Iran never won a war, but never lost a negotiation!" at 12.45pm today.
Previous US administrations have considered assassinating Soleimani before but decided that the fallout was too great a risk.
There is speculation on Twitter that the attack could have been a political move by Trump to distract from his impeachment.
Many of the comments and tweets are mocking the idea that there will be another world war, but there is underlying grave concern at the ramifications of the attack.