The United States may launch unilateral sanctions against North Korea, a U.S. special envoy Sung Kim said today. The statement came two days after North Korean fifth and biggest nuclear test in defiance of U.N. sanctions.

Speaking to media in Tokyo after meeting Japanese Foreign Ministry officials, Kim said, specific details of the U.S. unilateral sanctions are yet to be decided. He added both the U.S. and Japan are looking at a full range of possibilities, in terms of additional unilateral sanctions that can be implemented.

The UN Security Council denounced North Korea’s decision to carry out a powerful nuclear test on Friday and said it would immediately begin working on a resolution. The U.S., Britain and France pushed for the 15-member body to impose new sanctions.