WASHINGTON — American intelligence agencies say it is likely to take North Korea just one year to put the finishing touches on a missile that can reach the continental United States, according to several administration officials briefed on the new assessment.

Until a few weeks ago, the official estimate was that it would take roughly four years, give or take a year, for North Korea to develop a missile that could carry a nuclear weapon small enough to fit into the missile’s warhead and capable of surviving the stresses of re-entry and deliver it to the United States. But the realities of the past few months, especially a July 4 test, forced intelligence experts to conclude that their estimates have been too conservative. In the aforementioned test, a missile carried a warhead 1,700 miles into space and returned it at high speed in a sharp parabola. If the trajectory were flattened out, the missile could strike Alaska.

General Paul Selva, testifying before the Senate Armed Services Committee last week, said the most recent test stopped short of demonstrating that North Korea possesses “the capacity to strike the United States with any degree of accuracy or reasonable confidence of success.’’

But that statement went far beyond what most Pentagon officials had been allowed to say in public before the test. And it reflects a growing view, from the Defense Intelligence Agency to the CIA, that at this point North Korea’s missile engineers have cleared most of the major hurdles.

NEW YORK TIMES