Dhaka, May 13 -- The United States announced new sanctions Monday against Iran over its nuclear program, despite ongoing negotiations between the two countries over the sensitive issue.

The latest sanctions target three Iranian citizens and an Iranian entity with links to Tehran's Organization of Defensive Innovation and Research, also known by its Persian acronym SPND.

"Iran continues to substantially expand its nuclear program and carry out dual-use research and development activities applicable to nuclear weapons and nuclear weapons delivery systems," Secretary of State Marco Rubio said in a statement.

He said Iran is the only country in the world without nuclear weapons that enriches uranium to 60 percent purity.

That level far ex...