March 7, 2019 5:05 AM EST

New activity was detected at the Pyongyang factory which produced the country’s first intercontinental ballistic missiles (ICBMs) capable of reaching the U.S. mainland, Reuters reported Thursday.

Lawmakers briefed by Seoul’s intelligence service said cargo vehicle movement was seen at the Sanumdong factory.

South Korean spy chief Suh Hoon told the lawmakers that he perceives the activity as missile-related, Reuters reported, citing local Korean media.

Sanumdong produced “North Korea’s longest-range missiles which can fly over 13,000 km (8,080 miles),” according to Reuters.

On Wednesday, Suh Hoon told Yonghap News Agency that he believes uranium enrichment facilities at the Yongbyon nuclear complex are continuing to operate normally.

New work was also spotted on the Sohae missile launch. where Pyongyang reportedly began repairs late last week. President Donald Trump told reporters that he would be “very disappointed” if North Korea had started re-building the launch site.

The reports of new activity come just days after the collapse of a second nuclear summit between Trump and North Korean leader Kim Jong Un in Hanoi. According to the account from the U.S., the two sides parted without a deal after North Korea wanted all sanctions lifted in exchange for shutting down the Yongbyon site. Trump said that Kim had promised no further testing of rockets or missiles.

Pyongyang’s most recent recorded test of an ICBM was in November 2017.

Write to Amy Gunia at amy.gunia@time.com.

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