NASA's head Jim Bridenstine and Elon Musk addressed recent tensions 

Bridenstine says critical tweets were meant to hold SpaceX timelines to task

Previous tweets criticized the company for failing to meet schedules 

SpaceX's Crew Dragon capsule could fly humans to space in early 2020 

NASA Administrator Jim Bridenstine doubled down on critiques of SpaceX's outspoken leader, Elon Musk in a face-to-face press event on Thursday. 

During the conference, Bridenstine re-hashed Tweets criticizing SpaceX for failing to meet timelines for the development of its Crew Dragon spacecraft, saying  they were meant as a warning to all of the space agency's contractors about setting realistic development schedules.

'I have been focused on returning to realism when it comes to costs and schedules,' said the NASA Administrator.