Just days after the collapse of the Hanoi summit between U.S. President Donald Trump and Supreme Leader of North Korea Kim Jong-un, there are reports of Intercontinental Ballistic Missile (ICBM) activity on the north side of the Military Demarcation Line.

According to information from Reuters and the South Korean press, supply trucks were seen entering and leaving a munitions plant in Pyongyang. This plant is the same one that manufactures North Korea’s ICBMs, particularly the Hwasong-15. Business Day reported it has an estimated range of more than 8000 miles.

In addition to the activity reported in the Sanum-dong region, other groups watching the North Korean military stated this week the country is performing construction work at the Sohae launch facility. Portions of the Sohae base were deconstructed in 2018 as part of a partial agreement between the United States and the North Korean government, and the rest of the facility was expected to be torn down as well.

“I would be very disappointed if that were happening,” said President Trump while speaking to reporters about the issue. “It’s too early to see…It’s a very early report. We’re the ones that put it out. But I would be very, very disappointed in Chairman Kim, and I don’t think I will be, but we’ll see what happens. We’ll take a look. It’ll ultimately get solved.”

Missiles constructed at the Sanum-dong plant were operated from the Sohae spaceport in the past. In 2016, the North Koreans launched a Taepodong-2—also known as an Unha-3—from Sohae. The Taepodong-2 has a shorter range than the Hwasong-15, but according to analysts from Missile Threat, the weapon is capable of carrying chemical, biological, nuclear, or high explosive payloads. It’s also used to deliver satellites into orbit.

It’s unclear whether this new activity north of the 38th parallel is indicative of a reactivation of the country’s nuclear program or merely saber rattling. President Trump appears to want to leave the door open to further diplomacy with Kim Jong-un, at least in the short term. Other politicians in Washington fear that Kim may be using the Sohae facility to apply pressure on the White House to concede on issues the two countries were unable to work out in Hanoi.

“North Korea’s apparent work at this launch site raises the troubling possibility that yet again Kim Jong-un is more interested in garnering concessions than conducting serious, good faith efforts to denuclearize,” said U.S. Sen. Ed Markey, a Democrat from Massachusetts and member of the Senate’s East Asia Subcommittee.