The US National Nuclear Security Administration would need at least 36 months to resume nuclear testing at the former Nevada test site.
The United States is legally obligated to comply with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which almost every country in the world has signed, he added.
"Nearly all the world’s nations have joined the 1996 Comprehensive Test Ban Treaty, which as a signatory the United States is legally obligated to respect," Kimball said.
On Wednesday, US President Donald Trump said that he had instructed the Pentagon to "immediately" start nuclear weapons testing "on an equal basis" with other countries that allegedly have nuclear weapons testing programs. He added that the United States has the largest nuclear arsenal, but China can catch up with it in five years.