"The Missile Defense Review is still under way [and it] will address hypersonic threats," Trachtenberg told a meeting at the Heritage Foundation. "Our missile defense review is still under way. It has not been finalized yet."
Trachtenberg explained that the Missile Defense Review was designed to be wide in scope in order to assess other developing and emerging military technologies.
The Missile Defense Review is expected within a few weeks, according to The Hill. It is expected to align with the Pentagon's 2019 budget request for $12.9 billion toward ballistic missile defense and $3.9 billion for the Missile Defense Agency.
Meanwhile, David Trachtenberg said that the new US Nuclear Posture Review (NPR) was designed on the assumption that prospects for nuclear confrontations with both Russia and China have not declined.
"The 2010 review assumed prospects for nuclear confrontation with Russia and China had declined dramatically … reducing the salience of nuclear weapons in international affairs," Trachtenberg said in a speech at the Heritage Foundation. "[T]hese assumptions have not been born out."
The NPR was "grounded in a realistic assessment of today's strategic environment," he said.
Since the previous NPR had been conducted and published under President Barack Obama in 2010, "a much more challenging nuclear threat environment" had emerged, Trachtenberg added.