Closed-circuit television footage released Wednesday by the U.S. -run United Nations Command, which controls the southern part of the DMZ, showed the man making his escape.
Well, there was no sign of a breakthrough on the nuclear crisis, and the snub that Kim delivered to the envoy suggests that whatever proposal Song Tao brought with him from Kim Jong-un was not only rejected, but rejected in as offensive a way as possible.
This year, the North Korean's estranged half-brother Kim Jong-nam, was assassinated in broad daylight at Kuala Lumpur airport in an attack South Korean blamed on agents from the North.
Soldiers from the North sprint to the area, firing their weapons at the defector; one hurries across the dividing line before running back to the northern side.
The sanctions aim to further isolate Pyongyang, said Heather Nauert, a State Department spokeswoman, adding that she did not think targeting more Chinese firms would affect Beijing's cooperation on the North Korean issue.
Treasury also sanctioned two North Korean government agencies and five shipping companies alleged to have violated the sanctions.
UN Command spokesman Colonel Chad Carroll told journalists that one of the border guards ran across the military demarcation line for a "few seconds before returning back to the north side".
To allay his fears and reassure him he was indeed in the South, medical staff apparently placed a South Korean flag in his room and were also using psychotherapy.
North Korea has vowed never to give up its nuclear weapons programme, which it defends as a necessary defence against US plans to invade.
Seoul's foreign ministry said the US measure was "part of the international community's common efforts to bring North Korea to the path of denuclearisation through strong sanctions and pressure".
His spokeswoman confirmed the designation just after he made the remarks in front of reporters.
"Currently, the situation on the Korean peninsula is complicated and sensitive", Lu told a daily news briefing.
It has fired two missiles over Japan and on September 3 conducted its sixth and largest nuclear test.
The others include Iran, Sudan and Syria.
The sanctions included blacklisting three Chinese companies, Dandong Kehua Economy & Trade Co., Dandong Xianghe Trading Co., and Dandong Hongda Trade Co., which the Treasury Department said have done more than US$750 million (£566.73 million) in combined trade with North Korea.
Kim Yong-jin, a vice premier on education affairs in North Korea's cabinet, was reportedly executed for slouching during a meeting.