Tesla CEO Elon Musk, apparently salty because Amazon CEO and space rival Jeff Bezos achieved what Musk could not – launch a rocket then land it intact on Earth – took to Twitter to undermine the accomplishment.

Bezos' private space firm, Blue Origin, on Monday sent its unmanned New Shepard capsule nearly 333,000 feet, or about 62 miles, into the air – just above the internationally recognized boundary of space. The capsule landed under parachutes on the company's range in West Texas.

— Dan Primack (@danprimack) November 24, 2015

Musk's own rocket venture, SpaceX, has been trying to achieve the same feat, but to date has been unable to land the spacecraft on a barge at sea.

On Tuesday, Bezos celebrated the achievement, tweeting: "The rarest of beasts — a used rocket. Controlled landing not easy, but done right" along with a link to a video of the takeoff and landing.

— Jeff Bezos (@JeffBezos) November 24, 2015

Remarkably, it appears to be Bezos' first and, to date, only tweet. He has 39,000 followers, though, as of Wednesday evening.

Musk tweeted congratulations at first, but was unable to hold back. He sent out a few other tweets, including one that said: "Jeff maybe unaware SpaceX suborbital VTOL flight began 2013. Orbital water landing 2014. Orbital land landing next." VTOL is an acronym for vertical takeoff and landing.

— Elon Musk (@elonmusk) November 24, 2015

In a statement to Business Insider, Jessica Pieczonka, head of communications at Blue Origin, fired back at Musk.

"SpaceX is only trying to recover their first stage booster, which is of course suborbital. The SpaceX first stage does an in-space deceleration burn to make their re-entry more benign. If anything, the Blue Origin booster may be the one that flies through the harsher re-entry environment. Finally, the hardest part is probably the final landing segment which is the same for both boosters."

SpaceX so far has failed in its two attempts to land larger and more powerful Falcon 9 rocket boosters on an ocean barge. The company’s next attempt may come next month.