The International Olympic Committee and the National Olympic Committees of the two Koreas must agree to combining the women's hockey teams before such a roster change can be made.
North Korea will send a 550-member delegation to the games, which includes 230 cheerleaders, 140 artists and 30 taekwondo players for a demonstration.
South Korea and the Democratic People's Republic of Korea (DPRK) will repeat symbolic reconciliation events as seen in the past worldwide sports events as the two sides agreed to jointly march under one flag and cheer together during the upcoming Winter Olympics.
South Korean supporters wave unified flags at the World Student Games in August 2003 in Daegu, South Korea.The Korean Unification Flag features a blue silhouette of the peninsula and outlying islands.
North Korea is preparing a lavish display of its military strength in a parade on the eve of next month's Winter Olympics in the South, despite a rare sporting detente with Seoul, it was reported today.
"We reject a "freeze for freeze" approach in which legitimate defensive military exercises are placed on the same level of equivalency as the DPRK's unlawful actions", Tillerson said.
The two Koreas have joined forces at other worldwide sports events before.
North and South Korea by night, from the International Space Station.
But they are the most prominent steps towards rapprochement achieved by the two Koreas since they began exploring co-operation during the Olympics after a year of tension over the North's nuclear weapons program.
"We are turning the Pyeongchang Olympics that we've got into the Pyongyang Olympics", said Hong Joon-pyo, leader of South Korea's main conservative opposition party, referring to North Korea's capital.
Before the Games, the sides will carry out joint training for skiers at the North's Masik Pass resort and a cultural event at the Mount Kumgang resort, for which Seoul officials plan to visit the sites next week.
But he later said he suspected Russian Federation may not only be failing to implement some sanctions but "frustrating" some of the effort to press the North.
One of the most symbolic scenes during the PyeongChang Winter Olympics will be the ice hockey competition to be attended by the first joint Olympic team between the two Koreas. Pyongyang, which has rattled the worldwide community with its nuclear and missile tests in recent months, has agreed to send athletes to the Games and march with the South under one flag at the opening ceremony.
The two countries are still technically at war, because the 1950-53 Korean conflict ended with a truce and not a peace treaty.
Regarding sanctions on North Korea, he said that the United States is receiving evidence that worldwide sanctions are "really starting to hurt" North Korea, and praised China for putting pressure on Pyongyang.