U.S. President Barack Obama has arrived in South Korea on the second leg of an Asian tour, with a warning to North Korea against conducting a fourth nuclear test.
In a newspaper interview with South Korea's JoongAng Ilbo, released just before his arrival Friday, Mr. Obama said, "If North Korea were to make the mistake of engaging in another nuclear test, it should expect a firm response from the international community."
At a joint news conference later Friday with South Korean President Park Jeun-hye, Mr. Obama said America's commitment to South Korea would never waiver and the U.S. and South Korea would stand shoulder to shoulder against North Korean provocation.
The U.S. leader also expressed condolences to the families of the hundreds of children lost in last week's ferry accident.
Before Mr. Obama wrapped up a two-day visit to Japan earlier Friday, the two nations released a joint statement on security and trade. The countries said they share strong concern about China's air defense zone in the East China Sea, but reaffirmed interest in building productive ties with Beijing.
Following a Thursday meeting in Tokyo with Japanese Prime Minister Shinzo Abe, Mr. Obama explicitly stated the disputed Senkaku Islands fall under the treaty obliging the United States to defend Japan if attacked. Beijing also claims the islands, known as Diaoyu in China.
After two days in Seoul, Mr. Obama will head to Malaysia, where he will hold talks and attend a state dinner with Prime Minister Najib Razak. He will be the first sitting U.S. president to visit Malaysia since Lyndon Johnson traveled there in 1966.
Mr. Obama's last stop will be the Philippines, which is also involved in a territorial standoff with China and has deepened its military cooperation with Washington as a result.
This is Mr. Obama's fifth visit to Asia since taking office in 2009. He has promised to make the Pacific region a greater economic, diplomatic and military priority for the United States.