On Tuesday, the North abandoned that restraint, lobbing an intermediate-range ballistic missile at a normal angle and sending it over Hokkaido, into a spot in the Western Pacific almost 1,700 miles away. In doing so, Mr. Kim may have been trying to show that he can hit a faraway target, for the first time conducting a more realistic test of the type of missile he had threatened to use to strike near the American territory of Guam.
Indeed, Mr. Kim warned that his government could conduct more missile tests in the Pacific, North Koreaâs state-run news media reported on Wednesday.
While attending the launching of the missile, a Hwasong-12, on Tuesday, Mr. Kim said North Korea needed to conduct âmore ballistic rocket launching drills with the Pacific as a target in the future,â according to the Northâs official Korean Central News Agency. Mr. Kim called the test on Tuesday âa meaningful prelude to containing Guamâ and âa curtain-raiserâ of the Northâs âresolute countermeasures againstâ the joint military exercises that the United States and South Korea began last week.
Mr. Kim added that North Korea would continue to âwatch the U.S. demeanors as already declared and decide its future action according to them.â The 11-day military drills by Washington and Seoul, which North Korea has vehemently condemned as a rehearsal for war, are scheduled to end on Thursday, a potential excuse for North Korea to de-escalate.
Because of North Koreaâs location â squeezed between China and South Korea, with Japan to the east and southeast and Russia to the northeast â there is essentially no way that the North can test missiles on normal trajectories, as it did Tuesday, without sending them over another nation.
âIf the previous launchings were for testing technologies, this one was a realistic demonstration of an intermediate-range ballistic missile capability,â said Chang Young-keun, a missile expert at Korea Aerospace University near Seoul. âIn this test, the Northâs missile actually flew at a realistic angle and trajectory.â
North Korea rattled the Trump administration last month by launching two intercontinental ballistic missiles, the second of which demonstrated the potential to reach the contiguous United States. But officials and analysts doubted that the country had mastered the technology needed to protect a nuclear warhead from intense heat and friction as it re-entered the atmosphere from space.
Tuesdayâs test might have been most important for the development of more dependable intermediate-range missiles. But experts say it could also provide information for the crucial re-entry technology needed for a warhead on an intermediate-range missile to survive the fiery plunge back into the atmosphere.
It is less clear whether that information could help the North pursue the especially difficult goal of developing the re-entry technology needed to build a nuclear-tipped longer-range missile that could hit the mainland United States. Those warheads would re-enter more quickly, producing much higher heats.
The Hwasong-12 is an intermediate-range ballistic missile that the North says is designed to carry a large nuclear warhead. After the launch on Tuesday, the Japanese government sent a text alert to its people, advising them to take protective cover in case the test went wrong.
Japan said it did not try to shoot the missile down because it did not detect a threat to its territory. But analysts said the test nevertheless underlined some uncomfortable questions about the possibility of defending against such missiles.
The allies could do little more than track the missile Tuesday as it arched over Hokkaido and splashed into the northern Pacific. Analysts said Japan could have tried to shoot it down if its Aegis destroyers, which are armed with SM3 Block I interceptor missiles, happened to be in waters between North Korea and Japan. But because the SM3 is slower than the Hwasong-12, they would have had to make the attempt before the missile passed over the ships.
And one analyst noted that Japan could have been caught off guard entirely had the destroyers been elsewhere â for example, if Japan had ordered them south in response to North Koreaâs threat to fire missiles into the waters around Guam.
âAfter distracting attention toward Guam, North Korea fired the missile over Japan,â said Shin Jong-woo, a defense analyst at Korea Defense Forum, a Seoul-based network of military experts. âBy doing so, it reduced the chance of its missile being shot down, and at the same time demonstrated its ability to hit a target as far away as Guam without actually launching the missile in its direction.â
The United States and Japan were wrapping up a two-week joint military exercise around Hokkaido, which culminated in the demonstration of the PAC-3 missile-defense system on Tuesday. Kim Dong-yub, a defense analyst at Kyungnam Universityâs Institute for Far Eastern Studies in Seoul, noted that the missile flew too high for the PAC-3 to reach.
âI donât think it was an empty threat when North Korea warned it would fire the Hwasong-12 around Guam,â Mr. Kim said. âThe test today was the North Korean way of saying that it would go ahead with it and would be able to do it if the United States kept dragging its feet in coming to the negotiating table under the North Korean terms.â
Paul Burton, a Singapore-based director for Janeâs by IHS Markit, a defense analysis firm, noted that the North launched its missile Tuesday as the Trump administration was dealing with a calamitous storm in Houston. âThe timing of the test shows that the North Korean regime has an acute sense of how to cause maximum impact with its accelerated missile testing program,â Mr. Burton said.
South Koreaâs president, Moon Jae-in, responded to the launch by ordering his military to âdemonstrate a strong retaliatory capability against North Korea.â Four F-15K fighter jets soon dropped two bombs each at a domestic bombing range.
Even as North Korea continues to test missiles, South Korean intelligence officials told lawmakers in Seoul this week that the North was technically prepared to conduct its sixth underground nuclear test. Officials have speculated that the North might do so on Sept. 9, a North Korean holiday called the Day of the Foundation of the Republic, or that it might launch another missile on that date. The North conducted its last nuclear test on Sept. 9.