Trump made his remarks after the North Korea-focused 38 North website released recent satellite imagery that seems to show dismantlement underway at Sohae.
The Sanumdong factory produced two Hwasong-15 ICBMs, North Korea's furthest-reaching missile which can fly more than 13,000km, putting the the US East Coast within its reach.
Mr Pompeo, who visited North Korea, earlier this month for denuclearisation talks, had invited furore from Pyongyang, which later expressed its disappointment over the attitude of U.S. officials on denuclearisation, calling it "regrettable and really disappointing".
The Washington Post reports that North Korea appears to be building new ballistic missiles.
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The only group that offered measured support was the United Auto Workers. "Well, I think we have a lot of foes". China alone imported $12.3 billion of U.S. soybeans past year , according to the U.S.
North Korea's intention was to deceive the U.S.by misconstruing the number of warheads as well as research facilities they have, while claiming they have fully denuclearized, the Post reported, citing intelligence.
The North Korea flag flutters next to concertina wire at the North Korean embassy in Kuala Lumpur, Malaysia, March 2017.
While the intelligence reported on Monday does not suggest an expansion of North Korea's capabilities it shows work on advanced weapons is still ongoing, the Washington Post said.
Reuters also added that satellite imaging showed vehicles moving in and out of the facility, but not the extent of any missile construction.
US Secretary of State Mike Pompeo told the US Senate foreign relations committee last week that the North was still making fuel for nuclear weapons, but maintained the Trump administration was still making progress. Jeffrey Lewis of the James Martin Center for Nonproliferation Studies told the Post the site is "active".
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He also said that it was in the interests of Russian Federation and the USA to extend arms control treaties. White House press secretary Sarah Huckabee Sanders said they had not received a formal invitation .
"We see them going to work, just as before", a USA official told the Post.
USA intelligence agencies in recent months increased their estimates of the size of North Korea's nuclear arsenal, taking into account enriched uranium from at least one secret enrichment site.
Another US official was quoted by Fox News as saying that there was "no evidence" that Pyongyang stopped its work of building missiles, despite dismantling a nuclear test site recently.
Unidentified officials said U.S. spy agencies were seeing signs of construction at a large research facility in Sanumdong, suggesting ongoing activity in North Korea's nuclear and missile facilities. "The nuclear program provides them with a deterrent in their mind against regime change by the United States". "They are negotiating for recognition of their nuclear weapons".
In a joint declaration after the Jun 12 summit, the North Korean leader "reaffirmed his commitment" to work towards the "denuclearisation of the Korean Peninsula".
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Many analysts, however, said USA economic growth was boosted by temporary factors that will fade over the next few months. Private forecasters cautioned that the April-June pace may be unsustainable because it stems from temporary factors.
This indicated that there had not been a complete stop in activity during the summit talks.