Update: South Korea’s Joint Chief of Staff told the Wall Street Journal on Monday morning that reports of North Korea deploying landing craft towards the frontline are not true

As marathon inter-Korean talks entered their third day, North Korea deployed amphibious landing crafts carrying special forces towards the frontline, military sources said on Monday.

Approximately ten “air cushioned landing crafts” left their base in Cholsan and sailed forward to a naval base some 60km north of the Northern Limit Line, anonymous sources told South Korea’s Yonhap news agency on Monday.

The development comes as marathon negotiations between the two Koreas, which resumed on Sunday afternoon after an eleven hour break, appeared to be still be ongoing as of dawn on Monday morning.

“Negotiations are under way,” Blue House presidential spokesman Min Kyung-wook told South Korean reporters Monday morning, without revealing any details about progress.

An effective media blackout on negotiation progress is being observed, Min said, to avoid any negative effect on the outcome.

Despite the talks, South Korea is continuing to conduct regular propaganda broadcasts towards the North, something Pyongyang previously warned should stop or Seoul face the consequences.

And on Saturday the U.S. – South Korea joint WatchCon alert system was raised from three to two. WatchCon two is implemented on the peninsula when the threat from North Korea is deemed as being at a “vital” level.

In addition to moving landing crafts towards the border, intelligence sources said on Sunday that the North Korean side had also moved over 50 submarines from their bases, and deployed double the normal number of artillery units along the border.

The ongoing military maneuvers on both sides of the Koreas underscore the high pressure for negotiators to exit talks with a positive outcome, something that could be tricky to do given the sharp division.

The ongoing talks are being led by Hwang Pyong So, Pyongyang’s senior military political officer and South Korean National Security Adviser Kim Kwan-jin. Also present are South Korean Unification Minister Hong Yong-pyo and his DPRK counterpart, Kim Yang Gon.

The talks represent the first high-level contact between the two Koreas since a surprise meeting meeting between Hwang and Kim in October last year, which took place at the end of the Incheon Asian games.

Prior to the talks, North Korean state news outlet the Korea Central News Agency (KCNA) notably referred to South Korea by its official name – the Republic of Korea – for the first time since the current conservative party begun its administration in Seoul.