A North Korean long-range rocket launch site appears to have resumed “normal operation status,” American experts said Thursday.

The website 38 North and the Center for Strategic and International Studies used commercial satellite imagery to track construction at the site – which they said began before last week’s failed summit in Hanoi between Trump and North Korean leader Kim Jong Un.

Images taken on March 6 showed that a rail-mounted structure to transfer rockets to the launching pad appeared to have been completed and “may now be operational.”

Cranes have been removed from the pad and progress also appeared to have been made on the rebuilding of the support structure for a rocket engine testing stand.

“Given that construction, plus activity at other areas of the site, Sohae [Satellite Launching Station] appears to have returned to normal operational status,” 38 North’s report said.

The news comes at a difficult time for the Trump administration, which is already frustrated by the lack of progress on negotiations with the North, following the collapse of the second Trump-Kim summit in Vietnam’s capital.

Kim had agreed to close Sohae at a summit with South Korean President Moon Jae-in in Pyongyang as part of confidence-building measures, and satellite images in August indicated that workers were dismantling the engine test stand.

When asked Thursday if he was disappointed about the news, Trump said,  “We’ll see. We’ll let you know in about a year.”

The president had declared that it was “too early” to tell if a previous report about activity at the site was true, but said he would be “very, very disappointed in Chairman Kim” if the intelligence is verified.

US media had speculated over whether Trump might step up pressure on Pyongyang following the aborted summit, by intensifying an already crippling sanctions regime.

State Department spokesman Robert Palladino affirmed Washington’s commitment to remain engaged with Kim, telling journalists on Thursday that the Trump administration was ready for “constructive negotiation.”

Palladino would not say if Washington had been in contact with Pyongyang over Sohae, situated on North Korea’s northwest coast, or the failed Hanoi talks.

– with reporting by Agence France-Presse