For the third time since its inception in 1945, the UN Security Council will be chaired by a sitting US president.
Trump will use his position of power to call out Iranian commander-in-chief Hassan Rouhani and denounce what the White House sees as bellicose behaviour in the region.
US Ambassador to the United Nations, Nikki Haley, said: “I am sure that’s going to be the most watched Security Council meeting ever.”
Ms Haley’s predictions come after she urged Iran to “look in the mirror” before it accused the US of any involvement in a terrorist attack which occurred on Saturday in the southwestern city of Ahvaz in Iran.
Mr Rouhani implied US-backed nations were behind the shooting at a military parade in which at least 29 people were brutally murdered.
Speaking about the upcoming clash between Mr Trump and Mr Rouhani, one senior UN diplomat said: “I don’t think it will be that entertaining at all.
“Even those who don’t like him, the attitude of all other heads of state and government in a public meeting when faced with any president of the United States of America is to be on their best behaviour.”
Almost every UN member state is likely to send their Prime Minister or President to the Security Council meeting, except Russia and China who are expected to send ministers.
In a rare move, the Council is meeting at the head-of-state and government level.
Trump’s predecessor Barack Obama presided over meetings in 2009 and 2014 on nuclear nonproliferation and foreign terrorist fighters.
In both cases, the council adopted resolutions on the topics under discussion.
Ms Haley said there were no plans to adopt a resolution at Wednesday’s meeting.
She said: “We want to make sure Iran understands the world is watching.
“That’s the biggest reason for this meeting.”
The topic of the meeting will be nonproliferation of weapons of mass destruction, a broad issue that allows leaders around the table to raise a variety of subjects from North Korea to chemical weapons attacks in Syria.
However, Trump indicated his intentions to hone in on Iran and focus the discussion on the Middle Eastern nation.
In an unguarded tweet, he wrote: “I will chair a United Nations Security Council meeting on Iran.”
But an official US memo on the meeting made no mention of any other countries.
It read: “The purpose of this meeting is to discuss ways the Security Council can better enforce the resolutions it has adopted to counter the spread and use of the world’s most dangerous weapons.”