Seoul immediately responded to its northern neighbor’s latest act of provocation on Friday with military drills and its own missile test, raising fears about the arms race on the Korean Peninsula.

For the second time in less than a month, Pyongyang on Friday fired a ballistic missile that flew over Japan in what is widely seen as payback for the U.N Security Council’s latest sanctions.

The move comes hours after the pariah state threatened to use nuclear weapons to “sink” the world’s third-largest economy and reduce the U.S. to “ashes and darkness” for supporting the U.N. resolution.

In retort, the South Korean military conducted live-fire exercises that mimic attacking Pyongyang’s launch site, NBC News reported on Friday. President Moon Jae-in’s administration also said on Friday that the country conducted its own ballistic missile test into the sea, according to Reuters.

Seoul’s rapid comeback is widely viewed as justified and indicates the nation was prepared for North Korean hostilities. However, analysts called the venture risky, warning it could escalate an already-tense situation.

“As an American waking up in Seoul to news of this latest provocation, I’m unnerved by the image of missiles being launched into the skies by both Koreas,” said Jean H. Lee, global fellow at the Woodrow Wilson International Center for Scholars. “This is a very dangerous arms race.”

In a statement, South Korea’s Joint Chiefs of Staff said its military’s quick response represented combat readiness, Yonhap News reported. The country will be holding a National Security Council meeting later in the day to discuss the situation, while the U.N Security Council is also expected to convene.

“South Korea wants to show the world that it is not the only Korea that has advanced military capabilities …They want to make sure Kim Jong Un knows who he is dealing with, and that South Korea can go tit-for-tat in a conflict, even without the U.S.,” said Harry Kazianis, director of defense studies at The Center for the National Interest, a Washington-based think tank.

Still, Seoul’s retaliation may not be effective in deterring North Korea.

“To practice bomb drills when the enemy is conducting nuclear tests and ballistic missile tests hundreds of thousands of times as powerful as the conventional bombs the South is showcasing, there’s an element of futility, if not tragedy, to the South’s stand,” said Tufts University professor Sung-Yoon Lee.

Friday’s developments are of historical significance. The day marks the 67th anniversary of the American landing at Inchon, an important military offensive during the Korean War.