Gatland fanned the flames ahead of next week’s RBS 6 Nations opener in Cardiff by saying Hartley “imploded” against South Africa in November and “goes to pieces”.
But Johnson retorted: “He has said a lot of things. Warren is not particularly subtle. Dylan has been playing fantastically. He has played the game at the highest level at a very young age.
“He has matured incredibly. He has just led his team though a European stage unbeaten. He had a lot of provocation in Cardiff and he has done his talking on the pitch. I don’t think he has anything to prove to Warren Gatland.”
Johnson (below right) said he was not surprised that Gatland sought to raise tensions ahead of a Test in Cardiff that was never in danger of lacking spice.
“It’s not as if it wasn’t something that Warren has done before and it wasn’t unexpected,” he added. “I think Warren has gone a bit early, a bit premature. I’m sure he [Hartley] is handling it fine. He understands what it is all about – you don’t have to have a huge amount of experience to realise what is going on.
“It’s about pressure and how people react to it. Where Wales are, they are under pressure as a team with their performances and not winning a game for a while.”
Gatland responded: “At least my chief executive has not come out and said that I have to finish first or second.”
England captain Lewis Moody (left), who is set to miss the clashes with Wales and Italy due to injury, has backed Hartley to ignore Gatland’s sniping.
“You know if you have had a good or bad game,” said Moody. “Dylan has done an incredible job. You don’t pay attention, you just get on with your job.”