He did not directly refer to the training failures of the United States - despite investing more than $30 billion in equipping and training the Iraqi Army, four brigades forces disappeared in the face of the Isis (Islamic State) onslaught in Mosul last June.
But General Keating said New Zealand and other members of the coalition in the fight against Isis "have taken lessons from the past" and looked at the needs of the Iraqi security forces.
"It is not just about how our trainers will teach their counterparts, but it is vital for our trainers to better understand how Iraqi soldiers learn."
Part of the training would involve teaching Iraqis how to train.
"Success looks like Iraqi trainers being able to carry on the work of the New Zealand Defence Force and coalition, thereby creating an independent, self-sustaining capability for the Iraqi Government to call on."
Of the 143, up to 106 would be at Taji and the others would be based around the region but in support of the mission. Only 16 of the 143 were specialist trainers but others would be expected to help train as well. A portion of the deployment would be a protection force, made up of the regular arm.
The trainers as well as their NZDF protection force will be armed and able to defend themselves against attack. The New Zealanders will train them in planning operations but will not plan the operations themselves or have a role in them, General Keating said.
When Mr Key originally floated the deployment, in November last year, he thought the SAS could go in a force protection capacity but they are being held back - clearly in reserve in case the security situation worsens.
Mr Key began his case in a sombre fashion in Parliament, making the case for deployment against the jihadi fanatics who have butchered their way through northern Iraq.
New Zealand stands up for what's right and sending its forces to Iraq to help in the fight against Isis "is the right decision", he said.
By the time he had returned from the press conference with General Keating it had turned more passionate.
"This is the time to stand up and be counted," he shouted across the House to the Opposition. "Get some guts and join the right side."
He also revealed that the 35 to 40 Isis supporters on the watchlist of intelligence agencies in New Zealand had risen to 60 or 70 since November last year.
In a surprise move, Catholic bishops issued a statement of support for the deployment, saying "New Zealand can no longer watch from the sidelines as the Islamic State continues to inflict immense suffering and brutality on the people of Iraq. They must not be left to face such unjust aggression on their own".
The Government has not yet nailed down an agreement with the Iraqi Government for legal protection of the New Zealand Defence Force while they are there.
Mr Key said that unless there was one, the troops would not go but he is confident it will be settled.
Foreign Minister Murray McCully has been given responsibility for that.
The deployment will almost certainly be in conjunction with an Australian contingent but because the Australian Government is yet to announce it, Mr Key and General Keating would say it was only "probable".
The announcement may be being left until later in the week when Australian Prime Minister Tony Abbott visits New Zealand.
