美国有线新闻 CNN 朝鲜试射弹道导弹 用导弹完成与特朗普第一次通话（在线收听）

For the first time since U.S. President Donald Trump took office, North Korea has test-fired a ballistic missile. And we start today by explaining why that's significant.

First, the launch. It was done on Sunday. Officials believe the weapon flew a few hundred miles before it crashed into the Sea of Japan, also known as the East Sea. It's thought to be a medium range missile, one that could potentially hit South Korea, but not the United States.

Then, there was the timing. The launch came as President Trump was hosting Japanese Prime Minister Shinzo Abe in the U.S. Japan is an ally of both America and South Korea, and all three of those nations are considered rivals of North Korea. So, analysts say the North was trying to send a warning to Japan not to get too friendly with the new American president.

Prime Minister Abe called the launch intolerable and he told North Korea to abide by international law that it stop testing missiles. And President Trump said the U.S. stands by Japan 100 percent.

Why does North Korea test-fire missiles? Experts say it's partly to see how far the weapons can fly and what they're capable of. But also, to send a message, to remind other countries that North Korea has these things and they get media attention from around the world.