When asked if his intervention meant he had lost confidence in DHBs and the ministry to achieve safe staffing, he said he was motivated by the ongoing concerns expressed in the media by nurses about the issue.
"I accept that nurses don't feel that DHBs have always delivered on previous commitments. As minister I will be requiring DHBs to make good on all staffing commitments," said Clark, who noted the Government had already committed to funding an extra 500 DHBs nurses as part of the pay talks.
"It's clear we've been asking too much of our nurses and their workloads are not sustainable. The Government had heard the message from DHB nurses and midwives ... we agree safe staffing must be a priority."
Nurses' concerns about safe staffing go back to the early 2000s when NZNO wanted staff-to-patient ratios fixed. Nurses have complained of not having enough time to do their jobs properly.
Pay talks in 2005, when Labour led the Government, produced agreement to pursue something more sophisticated than ratios.
In the following 13 years this gradually developed into the "care capacity demand management" system. Yet only 14 of the 20 DHBs are said to be "actively engaged" in this safe-staffing scheme.
Clark's accord is another layer of monitoring to ensure the scheme is properly implemented - and DHB chief executives will be held tightly accountable - but this will take three more years. He has ordered quarterly reports from the ministry on progress.
When asked why it was taking 16 years in total to implement, Clark said he couldn't answer for previous governments. He wants DHB nurses and midwives to know that "this government cares about safe staffing".
NZNO members will start voting next week on the latest offer from DHBs to settle their pay dispute, which led to a 24-hour strike at public hospitals this month.
The offer includes stepped pay rises of around 12 to 13 per cent for many members by August next year.
NZNO has said it also includes funding "to provide immediate relief for staffing and workload issues", on top of existing commitments to fully implement the care capacity and demand management scheme.
The scheme ensures DHBs match demand and resources to ensure patient safety, a safe workplace and organisational efficiency.