North Korea’s continued advancement of its nuclear capabilities and strengthened ties with Russia have nudged a former U.S. intelligence official toward accepting South Korea’s need for its own nuclear deterrent, a sign of shifting thinking in Washington about a proposal considered beyond the pale for decades.

Speaking ahead of his panel at this year’s Asan Plenum in Seoul, former National Intelligence Officer for North Korea Sydney Seiler told reporters he’s now “less opposed” to the idea of ROK nuclear weapons than he was five years ago, reflecting deepening concern that Pyongyang has no intention of giving up its own weapons of mass destruction.