The new head of the U.N. nuclear test ban treaty organization says his goal is to have the treaty enter into force, which would require ratification by eight countries; the U.S., China, Iran, Israel, Egypt, India, Pakistan and North Korea.

Speaking at a news conference Robert Floyd said he remains optimistic, but is also realistic, not underestimating the challenge.

Floyd said he wants to sit down with each of the eight countries to discuss why five of them signed the treaty and understand their “current circumstances” regarding the treaty.

He said he would like to ask them, “What pathway do you see going forward so they could ratify?”

The Comprehensive Nuclear Test Ban Treaty, known as the CTBT, has 196 member states — 185 that have signed the treaty and 170 that have ratified it. But the treaty has not entered into force because it needs ratification by the eight non-ratifying nations that had nuclear power reactors or research reactors when the U.N. General Assembly adopted the treaty in 1996.

Floyd, who was previously the director-general of the Australian Safeguards and Nonproliferation Office, became executive secretary of the treaty organization Aug. 1 after being elected over his predecessor, Lassina Zerbo, who was seeking an unprecedented third term.

Floyd said that “the most immediate future ratifications will not be from the eight” nuclear nations adding that there are about 25 countries that haven’t ratified the treaty.

He noted that only one nuclear test explosion has been carried out in the 21st century — by North Korea. “CTBT has effectively created a norm against nuclear testing, even though it is yet to become legally binding.

He added that today there are more than 13,400 nuclear weapons in existence, which is enough to destroy the world many times over.