There are fears that South Korean players might be removed from the team to make room for North Koreans.
A 30-strong North Korean taekwondo delegation will also visit the South next month for demonstrations in Pyeongchang and Seoul.
"We all need to be very sober and clear-eyed about the current situation".
"It's apparent to us that they're not implementing all the sanctions and there's some evidence they may be frustrating some of the sanctions", Tillerson said aboard his aircraft while returning from Vancouver.
He would not say whether the United States has been considering a limited, pre-emptive attack to show the North that the United States means business.
"It is an absolutely unacceptable situation, when 17 countries take upon themselves the role of "helper" to the UN Security Council and interpreter of its resolutions, thereby actually putting its authority into doubt", the ministry said in a statement. They gave no details. Prior to the games, skiers from both nations will train together in North Korea. Ministers attending the talks in Canada agreed to raise pressure on Pyongyang.
"Only through dialogue, equally addressing the reasonable concerns of all parties, can a way to an effective and peaceful resolution be found", Lu added.More news: Motorola Moto Z3 Play review
The two sides agreed to let their athletes march together under a unified flag of the Korean Peninsula at an opening ceremony of the 2018 Winter Olympics and cheer together for both athletes from the two Koreas during the Winter Olympics that will run from February to March at South Korea's east county of PyeongChang. DPRK Today said: "At the talks both sides had a honest discussion on the practical matters related to the performances by the north side's art troupe to be dispatched to the south side's area with the 23rd Winter Olympics as an occasion".
"It is not the time to ease pressure, or to reward North Korea", he said. Russian Federation has denied breaching North Korea sanctions.
Seoul hopes that the ongoing inter-Korean talks, which are mostly limited to the Olympics, will pave the way for denuclearization talks between Washington and Pyongyang.
The agreements still require approval from the International Olympic Committee, but they are the most prominent steps toward rapprochement achieved by the Koreas since they recently began exploring cooperation during the Olympics after a year of heightened tension over the North's nuclear weapons program.
A senior State Department official said US Defense Secretary Jim Mattis briefed the Vancouver participants over dinner on Monday and stressed the US preference for a diplomatic solution, while keeping a military option on the table. "We especially urge Russian Federation and China in this matter", Tillerson said.
"Marching under the one peninsula flag does not bring peace to the Korean peninsula", said one South Korean Twitter user.
The International Olympic Committee has been more cautious.