Just one word.

That’s all Ford CEO Jim Farley used to respond to Tesla CEO Elon Musk on Friday.

“Tesla & Ford are the only American carmakers not to have gone bankrupt out of 1000’s of car startups. Prototypes are easy, production is hard & being cash flow positive is excruciating,” Musk tweeted Thursday.

Farley retweeted Musk early Friday saying only, “Respect.”

Reaction on Twitter has been swift with likes,