South Korea's military said Thursday there is no clear indication yet that another North Korean ballistic missile launch is near at hand amid reports of rain there.

"Currently, there's no sign of an imminent North Korean missile launch," Army Col. Roh Jae-cheon, spokesman for the Joint Chiefs of Staff, said at a press briefing. "Our military is continuing to closely monitor North Korea's every possible provocation, mobilizing combined surveillance assets with the United States."

Last week, the secretive North moved a truck-mounted transporter erector launcher to the vicinity of Kusong near the country's northwestern coast, according to foreign media, which quoted unnamed Pentagon officials.

If confirmed, it portends another missile provocation by the North following the July 4 firing of an intercontinental range ballistic missile.

The North has often timed its strategic provocations with key political occasions.

On Thursday, the two Koreas mark the 64th anniversary of the Armistice Agreement that ended the 1950-53 Korean War, although it has never been replaced by a formal peace treaty.

The pick of a missile test date is also affected by weather.

It's reportedly raining in Kusong, North Pyongyang Province.

But South Korean and US officials have grown concerned about the increasing unpredictability of the Kim Jong-un regime when it comes to its provocations.

The North has improved its ability to hide its preparations for a missile launch until the last minute.

CNN reported that the North carried out a missile ejection test at a naval shipyard in the eastern port city of Sinpo earlier this week. Citing a US defense official, the broadcaster said it was a ground test of a "cold-launch system" mainly used for a submarine missile.

The JCS official said, "It's assessed that North Korea is constantly working to develop the SLBM. We are keeping a close eye on related activity." SLBM means submarine-launched ballistic missile. He did not elaborate.

The nuclear-armed North is seen as honing its capabilities to hit the mainland US with its own timetable.

It threatened a nuclear strike on the "heart of the US" if it attempts to remove its leadership, infuriated by CIA Director Mike Pompeo's call for a way to "separate that regime from this (nuclear) system."

Should the North press ahead with another missile launch, it would deal a heavy blow to the South's renewed push for inter-Korean dialogue.

The left-leaning Moon Jae-in administration has proposed holding talks on easing border tensions and arranging family reunions.

Pyongyang has kept mum on the overture.

Seoul said it remains committed to efforts for bringing peace to the peninsula.

"There is no change in the government's determination and sincerity on dialogue," Moon Sang-gyun, spokesman for the Ministry of National Defense, told reporters.

He added his ministry is still waiting for the North's response to the dialogue offer.

Meanwhile, the North's armed forces are conducting summer drills.

This year's exercise features a sharp increase in the number of drone operations, said a defense source here. (Yonhap)