The third Nuclear Security Summit to open in The Hague on Monday is set to become an unexpected stage to test President Park Geun-hye’s diplomatic adroitness. Since she took office in February last year, Park has been successful in cultivating friendly ties with leaders of the neighboring powers, except for Japanese Prime Minister Shinzo Abe, who has angered South Koreans with his denial of Japan’s wartime wrongdoings.

During the two-day summit, which comes in the aftermath of Russia’s annexation of Crimea, however, Park will face the thorny task of striking a subtle balance among major powers over complicated issues.

She is to hold a trilateral summit with U.S. President Barack Obama and Abe on the sidelines of the international nuclear conference. Though not one-on-one, the meeting will mark the first formal talks between Park and Abe since they took office more than a year ago.

The three-way summit has been set up by the U.S., which has been pressuring its two closest allies in Asia to come to terms with each other over historical matters. A senior White House official said Friday the meeting would send “a powerful message about America’s commitment to the security of Northeast Asia.” The official emphasized the Obama administration remained focused on its policy of rebalancing toward Asia, which is viewed as mainly aimed at keeping a rising China in check.

Park made a right ― and inevitable ― decision to meet separately with her Chinese counterpart Xi Jinping on the margins of the nuclear summit. The meeting, the fourth between the two leaders, will be necessary for Seoul to alleviate Beijing’s uneasiness over its strengthened security cooperation with Washington and Tokyo.

South Korean officials are apparently concerned that Park’s three-way summit with Abe and Obama may give the Japanese leader a pretext for stopping short of taking sincere steps to atone for atrocities committed during Japan’s 1910-45 colonial rule of the Korean Peninsula. Such concern was reflected in their repeated remarks that the agenda for the meeting would be limited to the issues of global nuclear nonproliferation and the North Korea threat.

But Park needs to be active in raising historical issues with Abe in Obama’s presence. This may help leave no room for diplomatic misunderstanding and domestic political repercussions.

Both Park and Abe are likely to face a U.S. request to join in imposing sanctions against Russia for its annexation of Crimea. Seoul’s Foreign Ministry last week issued a statement saying South Korea would not recognize Russia’s move. Park may have to put forward a response that is more substantial and still falls short of harming ties with Moscow.