WASHINGTON - On the brink of an expected North Korean missile test, U.S. officials focused on the limits of Pyongyang's nuclear firepower Friday, trying to shift attention from the disclosure that the North Koreans might be able to launch a nuclear strike.

They insisted that while the unpredictable government might have rudimentary nuclear capabilities, it has not proved it has a weapon that could reach the United States.

A senior defense official said the U.S. sees a "strong likelihood" that North Korea will launch a test missile in coming days in defiance of international calls for restraint. The effort is expected to test the North's ballistic missile technologies, not a nuclear weapon, said the official, who was granted anonymity to discuss intelligence matters.

Unless the missile unexpectedly heads for a U.S. or allied target, the Pentagon does not plan to try to shoot it down, several officials said. As a precaution, the U.S. has arrayed in the Pacific a number of missile defense Navy ships, tracking radars and other elements of its worldwide network for shooting down hostile missiles.

The tensions playing out on the Korean peninsula are the latest in a long-running drama that dates to the 1950-53 Korean War, fed by the North's conviction that Washington is intent on destroying the government in Pyongyang and Washington's worry that the North could, out of desperation, reignite the war by invading the South.

The mood in the North Korean capital, meanwhile, was hardly so tense. Many people were in the streets preparing for the birthday April 15 of national founder Kim Il Sung - the biggest holiday of the year. Even so, this year's big flower show in Kim's honor features an exhibition of orchids built around mock-ups of red-tipped missiles, slogans hailing the military and reminders of perceived threats to the nation.

The plain fact is that no one can be sure how far North Korea has progressed in its pursuit of becoming a full-fledged nuclear power, aside perhaps from a few people close to its new leader, Kim Jong Un.

More is known about North Korea's conventional military firepower, and it is being heavily monitored for signs of trouble. The North has long had thousands of artillery guns positioned close enough to the border to hit Seoul with a murderous barrage on short notice. The U.S. has about 28,500 troops in the South.

Concern about the North's threatening rhetoric jumped a notch on Thursday with the disclosure on Capitol Hill that the U.S. Defense Intelligence Agency believes with "moderate confidence" that the North could deliver a nuclear weapon by ballistic missile. The DIA assessment did not mention the potential range of such a strike, but it led to a push by administration officials to minimize the significance of the jarring disclosure.

Secretary of State John Kerry said in Seoul on Friday "it's inaccurate to suggest" that the North had fully tested and demonstrated its ability to deliver a nuclear weapon by ballistic missile, a message also delivered by the Pentagon and by James Clapper, the director of national intelligence and a former head of the DIA.

Indeed, the attention-getting DIA report made no such suggestion; it simply offered what amounts to an educated guess that the North has some level of nuclear weapons capability. It has been working on that for at least 20 years, and private analysts who closely track North Korean developments say it's fairly clear that the North has made progress.

The DIA disclosure spawned a partisan split in Washington over its significance and meaning. A Republican House member with access to classified intelligence said the analysis was in line with a view generally held by other U.S. intelligence agencies, whereas a senior Obama administration official said the central DIA assertion is not shared by many government analysts.

Both officials spoke on condition of anonymity in order to discuss intelligence.

Rep. Adam Schiff, D-Calif., a member of the House Intelligence Committee, said Friday that members of the committee received an overall briefing on worldwide threats including North Korea this week, but they'll get a more detailed briefing next week.

"I'll be interested to see whether some of the other intelligence community take a different view" than the DIA assessment, he said.

Thomas Fingar, a former deputy director of national intelligence for analysis, said the DIA report reflects the fact that the military plans against worse cases, "so you're prepared for anything less than that."

Fingar, now a Stanford University professor, added, "That's different than judgments about what's 'most likely.' It gets into the subject of 'Is it conceivable?"'

Within the government's 16 intelligence agencies, analysts often disagree on even basic aspects of important issues. Deciphering the technical military advances in a reclusive society like North Korea is as much an art as a science, and the writers of intelligence reports are supposed to describe the degree of confidence in their sources in set terms.

The website of the director of national intelligence defines "high confidence" as indicating that "judgments are based on high-quality information, and/or that the nature of the issue makes it possible to render a solid judgment." Moderate confidence means "the information is credibly sourced and plausible but not of sufficient quality or corroborated sufficiently to warrant a higher level of confidence." Low confidence means the information's "credibility and/or plausibility is questionable, or that the information is too fragmented or poorly corroborated ... or that we have significant concerns or problems with the sources."

Kerry, who was headed to Beijing to seek Chinese help in persuading North Korea to halt its nuclear and missile testing, told reporters in Seoul that the North's progress on nuclear weapons, as described in the DIA report, pushed the country "closer to a line that is more dangerous." Kerry also was due to visit Japan.

"If Kim Jong Un decides to launch a missile, whether it's across the Sea of Japan or some other direction, he will be choosing willfully to ignore the entire international community," Kerry said. "And it will be a provocation and unwanted act that will raise people's temperatures."

The DIA report's assessment, written in March, was in line with a statement it issued two years earlier.

In March 2011, the agency's director, Lt. Gen. Ronald Burgess, told a Senate panel, "The North may now have several plutonium-based nuclear warheads that it can deliver by ballistic missiles and aircraft as well as by unconventional means."

David Albright, a leading North Korea expert at the Institute for Science and International Security, wrote in February, after the North's latest nuclear test, that he believes North Korea can mount a nuclear warhead on a shorter-range Nodong ballistic missile, whose estimated range of about 800 miles puts it within range of Japan.

"Pyongyang still lacks the ability to deploy a warhead on an ICBM (intercontinental ballistic missile), although it shows progress at this effort," Albright wrote.

Bruce Bennett, a Rand Corp. specialist on North Korea, said this week there is a "reasonable chance" that North Korea has short-range nuclear missile capability, but it is "very unlikely" that it has one that can reach the U.S.

While U.S. officials are watching for a missile test as early as this weekend, they are equally concerned about other actions the North Koreans might take to provoke a reaction either by the United States or South Korea.

Officials say that the U.S. has seen North Korea moving troops, trucks and other equipment arrayed along the Demilitarized Zone that separates the North and South. And they worry about the possibility Pyongyang could once again shell a South Korean island, torpedo a ship or perhaps fire artillery rounds at South Korean people or troops.

Limited attacks of that sort could be a greater threat because they would more likely result in injuries or deaths and could more quickly trigger a military response from South Korea or the U.S. and its allies.

Associated Press writer Lolita C. Baldor, AP White House Correspondent Julie Pace and AP broadcast correspondent Sagar Meghani contributed to this report.

Follow Robert Burns on Twitter at http://www.twitter.com/robertburnsAP