WASHINGTON — The black hole of North Korea intelligence gathering is getting blacker.

When President Obama and South Korea’s new president, Park Geun-hye, meet for the first time at the White House on Tuesday, intelligence officials and outside experts say, they will be working, by necessity, from a deeply incomplete understanding of their common adversary. At a time when the United States has learned to conduct drone strikes with increasing accuracy in Pakistan, and direct cyberweapons at specific nuclear centrifuges deep under the Iranian desert, its understanding of North Korea’s leadership and weapons systems has actually gotten worse.

The most recent intelligence failures included what administration officials now acknowledge was the C.I.A.’s initial judgment — now reversed — that the North’s young new leader, Kim Jong-un, was probably more interested in economic reform than in following his father’s and grandfather’s “military first” policy of bolstering the North’s missile and nuclear arsenals, and threatening to use them unless the world came to its door.

At the same time, North Korea’s ability to hide critical facts about its weapons capability has improved. Nearly three months after the North’s third nuclear test dangerously escalated tensions on the Korean Peninsula, the United States remains unable to answer the most crucial question about the blast: whether the country figured out a way to enrich uranium and dramatically speed its nuclear buildup. The North has managed to contain the telltale gases that would have provided the answer, thwarting American efforts to sniff out the evidence from Air Force sensors flown along the North Korean coast.

Since then, new mobile missile systems have appeared and then been whisked out of the view of spy satellites, leaving their whereabouts, to say nothing of their ability to reach Guam or the West Coast of the United States, uncertain. American officials said Monday that two missiles they once believed the North could launch imminently had been moved from launching sites, perhaps a sign that for now, at least, the North wants to de-escalate.