A confident and at times fiery Commander in chief was out to convince congress to vote in favour of the deal.
"This is the strongest non-proliferation agreement ever negotiated"
Mr Obama drew parallels to the Cold War, quoting JFK and republican President Reagan, as he defend his own pursuit of nuclear security.
In a direct appeal to US lawmakers he called for an end to the mindset of military action over diplomacy...
"the choice we face is ultimately between diplomacy and some form of war maybe not tomorrow, maybe not three months from now but soon".
The US has long been seeking to block Iran's pathways to a nuclear bomb, while Tehran maintains it's nuclear activities are peaceful. The current administration believes the deal will restrict Iran's atomic activities in return for the easing of painful international sanctions against the Islamic republic.
Mr Obama acknowledged the concerns of close ally-Israel but was steadfast in telling the country's Prime Minister that he was wrong to dismiss the agreement.
But on the eve of Mr Obama's speech Benjamin Netanyahu used a webcast to do just that...
"It will spark a nuclear arms race in the region and feed Iran's terrorism and aggression that would make war, the most horrific of all, far more likely".
Answering the critics, The US President was keen to point out that many of those who supported America's invasion of Iraq in 2003 were the same lawmakers standing against the nuclear agreement. And that attempts to kill the deal showed an ignorance of the bigger picture.
A congressional review of the deal is already halfway through a 60-day period before it goes to a vote, with some key democrats like Senator Chuck Schumer still uncertain on their position...
"This is such an important decision that I will not let pressure, politics or party influence"
If more than two thirds of congress go against the agreement President Obama will lose his veto power and the administration's long-sought nuclear deal will be stopped dead in its tracks.
For CRI I'm Kevin McAleese in Washington.
