North Korea fired several cruise missiles toward the West Sea on Wednesday, the South Korean military said, the latest in a series of saber-rattling that heightened tensions.

The Joint Chiefs of Staff said the North's launch took place around 7 a.m. but did not elaborate, citing an ongoing analysis.

"While strengthening our monitoring and vigilance, our military has been closely coordinating with the United States to monitor additional signs of North Korea's provocations," the JCS said in a text message sent to reporters.

According to sources, the missiles flew in a circular trajectory in waters west of the North Korean capital Pyongyang, similar to cruise missiles that fly at a lower altitude than ballistic missiles.

"The range was not short, and it is was presumed to have been launched from the ground," the source said, speculating that the cruise missiles were likely Hwasal-1 or -2, which are capable of carrying a Hwasan-31 nuclear warhead.

It marks the North's first cruise missile launch since September 2023, when it test-fired two long-range strategic cruise missiles with mock nuclear warheads toward the West Sea.

The latest launch comes 10 days after Pyongyang test-fired a solid-fuel intermediate-range ballistic missile carrying a hypersonic warhead into the East Sea in its first missile launch this year.

Hypersonic missiles are considered harder to detect and shoot down as they fly at speeds of at least Mach 5 -- five times the speed of sound -- and are highly maneuverable and able to change course during flight.

Last week, North Korea claimed it has tested an underwater nuclear weapons system under development in response to the latest joint maritime exercise involving South Korea, the United States and Japan.

Tensions remain high along the inter-Korean border as buffer zones created under a 2018 inter-Korean military agreement became invalid following North Korea's conducting of live-fire drills near the western maritime border earlier this month.

The South Korean military said it will resume artillery firings and drills near the border as Pyongyang's shellings near the Northern Limit Line, the de facto maritime border in the West Sea, scrapped the mutually agreed buffer zones.