The presidential office is communicating with China after Beijing sounded out Seoul about President Lee Jae Myung attending a military parade in September to mark the 80th anniversary of China’s victory over Japanese aggression at the end of World War II.

In a notice to the press on Wednesday, the office of presidential spokesperson Kang Yu-jung said while the two sides are in talks over the September 3 event at Tiananmen Square in Beijing, there are difficulties in disclosing details of the diplomatic communication.

The top office said Seoul and Beijing are closely communicating based on a consensus to further develop bilateral ties ahead of this year’s Asia-Pacific Economic Cooperation summit in Gyeongju.

Whatever Lee decides, the event is expected to put his administration’s foreign policy to the test as the country wrestles to achieve a diplomatic balance between its ally the U.S. and one of its major trading partners, China.

The last South Korean leader to attend the event was former President Park Geun-hye, who went in 2015 in hopes of encouraging Beijing to play a constructive role in resolving the nuclear issue with North Korea.