An American think-tank has said that activity has been detected at a North Korean long-range rocket site, suggesting Pyongyang may have taken up “rapid rebuilding” of a test facility, AFP reported on Wednesday. This comes a few days after talks between the United States and North Korea in Vietnam’s Hanoi ended without an agreement.

Center for Strategic and International Studies said activity was evident at the Sohae Satellite Launching Station – the facility from which Pyongyang launched satellites in 2012 and 2016. The activity was found based on analysis of satellite imagery of the launch station located at Dongchang-ri.

North Korean leader Kim Jong-un at a summit with South Korean President Moon Jae-in in September last year had pledged to close the Sohae launch site and allow international experts to observe the dismantling of the missile engine-testing site and launch pad, according to The Guardian.

“This facility had been dormant since August 2018, indicating the current activity is deliberate and purposeful,” said Joel Wit, director of 38 North, a US think tank monitoring Pyongyang. Wit said the evidence was not necessarily “consistent with preparations for an ICBM [intercontinental ballistic missile] test”.

“Aside from the fact that DPRK has never tested an ICBM from Sohae – it’s a space vehicle launch site – preparation for any launch would require a wide range of activities not observed in the imagery,” Wit said. Satellite images seen by 38 North showed that structures on the launch pad had been rebuilt sometime between February 16 and March 2.

Officials briefed by South Korea’s National Intelligence Service said work was taking place at the Dongchang-ri launch site and involved replacing a roof and a door at the facility, South Korea’s Yonhap News Agency reported.

US National Security Advisor John Bolton on Tuesday said the US was planning to increase sanctions on North Korea if Pyongyang did not scrap its nuclear weapons program, according to Fox News.