The US has been tracking Russia's nuclear-powered underwater drone project following a 2015, Russian "leak", which revealed plans of the underwater drone, complete with images of what the government-aligned television station NTV said was its nuclear warhead.
One area for improvement is infrastructure to test the weapons, Walker said.
Russia's embassy to the United States of America issued a separate statement, pointing out that the Sarmat missile Putin showcased is within the provisions of the 1982 INF treaty. "This is also fantastic, just like the weapons I mentioned yesterday [on March 1 in the State of the Nation Address - TASS]", the head of state said.
"We have said that the creation of global missile defense system by Washington will lead to nothing".
The AP said some of the entries are of the four-letter variety while others are digs at the U.S.
On Thursday, in his speech to the Federal Assembly Russian President Vladimir Putin unveiled the most advanced systems of strategic weapons, developed in response to Washington's unilateral withdrawal from the Anti-Ballistic Missile Treaty (ABM Treaty) and practical deployment of missile shield elements both inside the U.S. and outside its borders.
News about the deliberations at the Pentagon comes a day after Russian strongman Vladimir Putin threatened the USA by announcing new weaponry - including a nuclear-powered missile that can evade defense systems and hit any spot on the globe.
Hypersonics are generally defined as missiles than can fly more than five times the speed of sound.
"We are not surprised by (Putin's) statement, and the American people should rest assured that we are fully prepared", Pentagon spokesperson Dana White said.
Another proposed calling it "Thaw", adding in a note of sarcasm that it would finally help warm the ties between Russian Federation and the U.S.
She also accused Russian Federation of violating a 1980s missile treaty.
Putin, a former KGB officer who has brought many veterans of Soviet-era security agencies into high positions, is set to secure a new six-year presidential term in a March 18 election.
"This has to go through official channels, not through the press or yelling and hollering in the United States Congress", Putin said. It was Kelly's second interview with the Russian leader.