Kerry, who is headed to Beijing to seek Chinese help in persuading North Korea to halt its nuclear and missile testing, told reporters in South Korea 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 is 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, which has an estimated range of 800 miles, placing Japan within its range.
"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 United States.
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, South Korea or Japan.
Officials said the United States has seen North Korea moving troops, trucks and other equipment along the Demilitarized Zone that separates the North and South. They say they are concerned about the possibility that 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 more likely would result in injuries or deaths, and could more quickly trigger a military response from South Korea, or the United States and its allies.