When nuclear-armed North Korea fired a ballistic missile over Japan this week, it sparked international condemnation. But it also raised the question: Why Japan?

Millions of Japanese awoke to ominous text messages Tuesday warning them to take cover as a North Korean missile flew overhead, with one train operator bluntly explaining its halted service as "Reason: Ballistic missile launch."

North Korea revealed plans for the development of its missile program on Wednesday, as leader Kim Jong-Un ordered stepped-up production of rocket engines and intercontinental ballistic missile (ICBM) nosecones.

Chinese President Xi Jinping made a plea for cool-headedness over escalating tensions between the U.S. and North Korea in a phone conversation with U.S. President Donald Trump on Saturday, urging both sides to avoid words or actions that could worsen the situation.

The call came after Trump unleashed a slew of fresh threats against North Korea on Friday, declaring the U.S. military "locked and loaded" and warning North Korean leader Kim Jong Un that he "will regret it fast" if he takes any action against U.S. territories or allies.

Hours before proposed military talks between South and North Korea, Pyongyang on Thursday still refused to confirm its participation, officials said.

The U.S. House of Representatives on Thursday overwhelmingly voted in favor of broadening sanctions against North Korea, including efforts to cut the regime's sources of international financing.

Lawmakers voted 419 to 1 for the bill, which now heads to the Senate.

An official North Korean website warned Monday that Pyongyang will "wipe out" the United States if Washington starts a war on the peninsula, the latest tit-for-tat saber-rattling that has sent tensions soaring in the region.

Japanese Prime Minister Shinzo Abe on Tuesday called for a peaceful resolution to tensions surrounding North Korea as he began talks with visiting U.S. Vice President Mike Pence.

North Korea test-fired a missile early Sunday, hours before U.S. Vice President Mike Pence arrived in Seoul for talks on curbing Pyongyang's weapons programs, but U.S. officials said it exploded seconds after launch.

North Korea Sunday staged its first ballistic missile test since Donald Trump took office, a move denounced by Japan's leader who won "100 percent" backing from the new U.S. President.