A senior U.S. official has cast doubt over whether U.S. athletes will able to compete at the 2018 Winter Olympics in South Korea amid heightened tensions with the North.

U.S. Ambassador to the United Nations, Nikki Haley, said the prospect of U.S. athletes participating in February was an “open question.”

When asked by Fox News Wednesday night if it was a “done deal” for American athletes to participate in South Korea, Haley replied: “I have not heard anything about that … But I do know in the talks that we have, whether its Jerusalem or its North Korea, it’s always about how we protect U.S. citizens in the area.”

The Winter Olympics are due to be held from February 9-25 in Pyeongchang. The South Korean town is approximately 50 miles from the heavily fortified demilitarized zone (DMZ) on the border between the two Koreas.

Geopolitical tensions on the Korean Peninsula have increased substantially in recent months after North Korea’s latest missile and nuclear tests, conducted in defiance of international pressure and UN resolutions.

The hostile situation regarding North Korea is “changing by the day,” Haley said on Fox News, making the security of U.S. athletes somewhat uncertain. However, Haley said President Donald Trump’s administration would try to find the “best way” to ensure the athletes were protected.

On Thursday, North Korea’s Foreign Ministry reportedly said large military drills being carried out by the U.S. and South Korea — as well as the threats of pre-emptive war against Pyongyang by the U.S. — have made an outbreak of war on the Korean Peninsula an “established fact.”

When commenting on the American athletes hopeful of competing at the Games, Haley said Pyeongchang was “a perfect opportunity for all of them to go and do something they have worked so hard for. What we will do is, we will make sure that we’re taking every precaution possible to make sure that they’re safe and to know everything that’s going on around them.”

Earlier this week, it was announced Russia would be banned from competing in the Winter Olympics after “systemic manipulation” of anti-doping laws.

In September, French Sport Minister Laura Flessel said the country’s athletes would not take part in Pyeongchang if the nuclear threat from North Korea worsened and security of those in attendance could not be guaranteed.

—Reuters contributed to this report.