Department of Defense officials sought to answer this week the question of how the United States fell behind in hypersonic weapon development and what it is now doing to catch up with Russia and China.

“That’s one we get a lot, really,” Mike White, assistant director for hypersonics at the Pentagon, said at a Monday press briefing, responding to a question from the Washington Examiner as to how Russia already has tested weapons and the U.S. is still in the experimental phase of hypersonic missile development.