"Russia continues to modernize its delivery systems capable of launching from distances not previously seen," Robinson told a hearing of the US House of Representatives Armed Services Subcommittee on Strategic Forces on Tuesday.
Undersecretary of Defense for Policy John Rood told US policymakers at the same hearing that they take very seriously the capability of Russia and China's hypersonic weapons research and development.
"We are very seriously concerned about the rate of development we see [in hypersonics] in China and also in Russia," he said.
However, Robinson said that North Korea today posed the most immediate threat to the United States.
"North Korea remains the most immediate threat to our homeland," Robinson told a hearing of the US House of Representatives Armed Services Subcommittee on Strategic Forces on Tuesday.
Robinson added she remained confident that the already-deployed force of US Ground-Based Mid-course Interceptors mainly deployed at Fort Greely, in the US state of Alaska was sufficient to defend the United States against any long-range missile threat from North Korea.
"I'm confident the mid-course [interceptors] can defeat that threat today," she added.