North Korea launched suspected ballistic missiles toward the sea on Tuesday, according to South Korea and Japan, amid rising tensions with Seoul.

The launch followed North Korean threats over alleged South Korean surveillance drone flights, which Seoul has denied.

Analysts say the accusations and weapons tests are likely aimed at stoking anti–South Korea sentiment ahead of an upcoming Workers’ Party congress.

In recent months, North Korea has tested hypersonic missiles, cruise missiles, and anti-air weapons, while highlighting its nuclear deterrence goals, NBC News has reported.

Experts believe the launches are meant to showcase military achievements ahead of the major political meeting.