Iranian missile experts were present at a failed North Korean rocket launch last week, according to foreign media.
The missile blew up over the Yellow Sea soon after laucnhing, but the presence of Iranian experts underscores the close ties between the countries, both of which threaten international stability with nuclear weapons programs.
A dozen Iranian experts and executives present at the launch are from the sanctioned Shahid Hemmat Industrial Group in Iran.
"The Iranians undoubtedly were there to observe the missile launch and receive test data from North Korea," a diplomatic source was quoted as telling the Yonhap news agency.
Korea, Iran and Syria have long been suspected of working together, and several North Korean scientists reportedly were killed four years ago when Israel clandestinely bombed a nuclear structure under construction in northern Syria.
A Shabab ballistics missile developed in Iran is seen by analysts as a replica of North Korea’s mid-range Nodong missile.