South Korea is under a heightened alert, assessing how the widening crisis in the Middle East could impact its national security after the unprecedented attack that Palestinian militant group Hamas launched against Israel.

South Korean National Security Adviser Cho Tae-yong is examining possible impacts that the Hamas-Israel conflict could have on South Korean security as he is being briefed on the situation, said the office of President Yoon Suk Yeol on Monday.

The Hamas attack against Israel on Saturday, the deadliest assault it experienced in 50 years, appeared to be expanding into a full-scale war on the third day of the conflict.

The Israeli military has mobilized 300,000 reservists Monday as it moves on a full offensive in response to the surprise attack by ground, air, and sea by Hamas. Israel is also imposing a complete blockade of the Palestinian-controlled Gaza Strip.

South Korea condemned Hamas for its attack on Israel and expressed deep concern about civilian casualties.

The rapidly growing conflict elevated South Korea’s concern over a possible U.S. shift in priority to the Middle East and as a result, diminished support for deterring North Korea, according to analysts.

Cho Han-Bum, a senior research fellow at the Korea Institute for National Unification, a think tank in Seoul, said if the Palestinian-Israel conflict prolongs to the point that it requires the U.S. to deploy significant military capacity to the region, deterring North Korea could lower priority for the U.S.

Robert Manning, a senior fellow at the Stimson Center’s Reimagining U.S. Grand Strategy project, said U.S. extended deterrence could potentially be affected if “a military contingency” arose in the Middle East that demands significant U.S. military support.

“As the U.S. carrier group and emergency military aid to Israel highlight — events in the Middle East and in Europe, where the Ukraine war resulted in increased U.S. commitments in Europe indefinitely — are pulling the U.S. in directions that create tensions with the idea of Asia/China as the top priority and challenge, as spelled out in the White House national security strategy,” said Manning.