专家表示，朝鲜仍然缺乏将核武器打到美国本土的必要技术。
But the same experts admit that North Korea's test of an intercontinental ballistic missile, or ICBM, last week marked an improvement in its military program.
但是这位专家也承认，朝鲜上周进行的洲际弹道导弹测试是其军事计划有所提升的标志。
The ICBM that North Korea tested on July 28 was the second long-distance rocket it launched in the month of July. The missile tested is called the Hwasong-14. Defense officials in the U.S. and South Korea said the military launched it from the Mupyong-ni arms factory in the country's north.
朝鲜7月28日测试的弹道导弹是该国七月份发射的第二枚远程导弹。这枚试射的导弹被称为火星14型导弹。美韩国防官员表示，朝鲜军方从该国北部的武坪里军工厂发射了这枚导弹。
The missile traveled a distance of about 1,000 kilometers. But it reached an altitude of about 3,700 kilometers. It was in flight for about 45 minutes before falling into the sea. The missile crashed into the waters 175 kilometers from Hokkaido, Japan's second largest island.
这枚导弹飞行了大约1000公里的距离，但是达到了约3700公里的高度。导弹在坠入大海之前飞行了大约45分钟，然后坠入了距离日本第二大岛屿北海道175公里的水域。
Jonathan McDowell is an astrophysicist at the Harvard-Smithsonian Center for Astrophysics. He told VOA's Korean service that it appears North Korea has a fully operational ICBM. He said, "It seems to have worked as designed, and so that is a milestone in their missile development."
乔纳森·麦克道尔（Jonathan McDowell）是哈佛史密森天体物理学中心的天体物理学家。他对美国之音朝鲜分部表示，这表明朝鲜全面掌握了洲际弹道导弹。他说：“它看上去完全实现了设计方案，所以这是该国导弹发展的一座里程碑。”
McDowell noted that the military did not launch the rocket into the atmosphere in a normal way in order to travel the greatest distance. If it had, the rocket's weapons system could have traveled further.
麦克道尔指出，军方没有以常规方式发射导弹进入大气层从而飞行更远距离。如果他们这样做的话，该导弹的武器系统可能会飞得更远。
An earlier test on July 4 showed the furthest the Hwasong-14 could reach was between about 7,000 and 8,000 kilometers. This means it would have been able to reach Alaska.
7月4日进行的前一次导弹试射表明，火星14型导弹最远可以达到大约7千到8千公里之间。这意味着它原本可以打到阿拉斯加。
Experts continue to debate how North Korea was able to improve the missile's performance. McDowell suggests that higher-powered engines driving the rocket during its second stage could have given it "a bit more push."
专家们仍在讨论朝鲜如何得以改善其导弹性能。麦克道尔暗示，在第二阶段驱动导弹的高功率发动机可能赋予了它更大的推力。
The technology that directs missiles back to earth after launching has been one of the biggest problems for North Korea. And many experts doubt that North Korea's military has perfected that technology.
在导弹发射之后引导其重新返回地球的技术一直是朝鲜面临的最大难题之一。很多专家怀疑朝鲜军方已经完善了这项技术。
The weapons systems must be able to survive the extreme heat and pressure generated from traveling through the atmosphere. If not, ICBMs armed with nuclear weapons will not reach their targets.
武器系统必须能够承受穿越大气层的巨大的热量和压力。如果不能，装备核武器的洲际弹道导弹就无法命中目标。
There are additional doubts about North Korea's missile technology. They come from video by the Japanese public news agency NHK. The video showed the Hwasong-14 possibly falling apart as it landed in the waters off Hokkaido.
还有人对朝鲜的导弹计划存有疑问。这些疑问出自日本公共新闻机构NHK的短片。该短片显示，火星14型导弹在坠入北海道水域时可能已经解体。
Michael Elleman is a senior fellow for missile defense at The International Institute for Strategic Studies. He said that small, bright objects appeared to be falling off the missile as it returned to earth. This could be showing that the missile was breaking apart too soon.
迈克尔·埃尔曼（Michael Elleman）是国际战略研究所的导弹防御高级研究员。他说，这枚导弹在重新返回地球时似乎有小块、闪亮的物体掉落。这可能表明导弹过早解体。
Other experts, however, have suggested that the missile breaking apart may have been due to the steep angle of its flight path. The steep angle would have increased its speed and also its surface heat.
然而其他专家认为，这枚导弹解体可能是因为其飞行路径的角度太大。角度太大将会增加其速度和表面温度。
Elleman wrote on the website 38 North, which reports about North Korea:
埃尔曼在报道朝鲜的38 North网站上写道：
"A reasonable conclusion, based on the video evidence, is that the Hwasong-14's re-entry vehicle did not survive during its second test."
“根据视频给出的证据，可以合理推断火星14型导弹的再入飞行器在第二次试射中未能顶住。”
He wrote that North Korea has more work to do before the country's leader Kim Jong Un has a missile able to strike the American mainland.
他写道，在朝鲜领导人金正恩拥有可以打击美国本土的导弹之前，朝鲜还有很多工作要做。
But McDowell notes that it will only take the country a few more years to reach the level of technology it desires
但是麦克道尔指出，该国只需几年就能达到这种导弹所需的技术水平。
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I'm Jill Robbins.
我是吉尔·罗宾斯。
And I'm Pete Musto.
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