After autumn defeats against Fiji, Australia and South Africa, the WRU announced it would be conducting a review into performances, led by Tierney.

Tierney presented the review's findings to a WRU board meeting this week.

While Gatland remains in post, the New Zealander has been warned there will be a further review of performances after the tournament.

"I have had a number of honest conversations with Warren and I will make no secret of the fact his position was on the line as we undertook our review," said Tierney.

"Further than that, like any head coach in any sport, he knows the security of his position is directly related to the performances of the team and this is a situation that will continue to intensify.

"There is a tough challenge ahead but Warren is more than up for that challenge. We also believe he is equal to it."

Tierney says the WRU board considered more wholesale immediate changes but concluded that challenging Gatland to change Wales' fortunes on the pitch was the best approach.

"We have assessed in detail the planning and preparation, the enabling and controllable factors which are the responsibility of the coaches as well as the culture in camp, the mental fortitude of players, their experiences to date and their own heartfelt thoughts on the direction of travel for the squad," said Tierney.

"We have included expertise and opinion from a wide range of reputable and knowledgeable sources and we have seen what many pundits and fans have expressed, that we are not performing to our potential at the moment."