Analysts see a direct attack on Seoul as extremely unlikely, and there are no overt signs that North Korea's army is readying for war, let alone a nuclear one.
In Pyongyang, there were no signs of a military buildup. Scores of people were armed on a cold spring day with shovels, not guns, and were busy planting trees as part of a forestation campaign. The national flag fluttered across the city as North Korea marked the 20th anniversary of late leader Kim Jong Il's appointment as chairman of the National Defense Commission, and workers began preparing the city for the April 15 birthday of late President Kim Il Sung's birthday.
South Korea's military has reported missile movements on North Korea's east coast, but nothing pointed toward South Korea.
"The situation on the Korean Peninsula is inching close to a thermonuclear war due to the evermore undisguised hostile actions of the United States and the South Korean puppet warmongers and their moves for a war against" the North, said a statement by the North Korean Asia-Pacific Peace Committee, an organization that deals with regional matters.
The statement is similar to past threats that analysts call an attempt to raise anxiety in foreign capitals.
Analysts see the threats of war as a bid to win Pyongyang-friendly policy changes in Seoul and Washington. Last week, North Korea told foreign diplomats in Pyongyang that it will not be able to guarantee their safety starting Wednesday. It is not clear what significance that date holds.
Observers also say the torrent of North Korean prophecies of doom and efforts to raise war hysteria are partly to boost the image and military credentials of young leader Kim Jong Un.
Air Koryo's daily flight from Beijing was only half full on Tuesday. Flight attendants in red suits and blue scarves artfully kept in place by sparkling brooches betrayed no sense of fear or concern.
Among the tourists who arrived Tuesday was Mark Fahey, a biomedical engineer from Sydney, Australia, who said he thought a war was "pretty unlikely."
Fahey, a second-time visitor to North Korea, said he booked his trip to Pyongyang six months ago, eager to see how North Korea might have changed under Kim Jong Un. He said he chose to stick with his plans, suspecting that most of the threats were rhetoric.
"I knew that when I arrived here it would probably be very different to the way it was being reported in the media," he told The Associated Press at Pyongyang airport. He said his family trusts him to make the right judgment, but "my colleagues at work think I am crazy."
He said he took no special precautions. "I haven't brought anything at all - just a camera," he said with a laugh. But he noted that several other tourists who had been slated to travel with his group had canceled their journeys.
Chu Kang Jin, a Pyongyang resident, said everything is calm in the city.
"Everyone, including me, is determined to turn out as one to fight for national reunification ... if the enemies spark a war," he said, using nationalist rhetoric employed by many North Koreans when speaking to the media.
South Korean President Park Geun-hye, who has sought to re-engage North Korea with dialogue and aid since taking office in February, expressed exasperation Tuesday with what she called the "endless vicious cycle" of Seoul answering Pyongyang's hostile behavior with compromise, only to get more hostility.
U.S. and South Korean defense officials have said they've seen nothing to indicate that Pyongyang is preparing for a major military action, and there was no sign of an exodus of foreign companies or tourists from South Korea.
Still, the United States and South Korea have raised their defense postures, as has Japan, which deployed PAC-3 missile interceptors in key locations around Tokyo on Tuesday as a precaution against possible North Korean ballistic missile tests.
In Rome, U.N. Secretary-General Ban Ki-moon described the tensions on the Korean Peninsula as "very dangerous" and said that "any small incident caused by miscalculation or misjudgment" may "create an uncontrollable situation."
Also Tuesday, North Korea pulled out more than 50,000 workers from the Kaesong industrial park, which combines South Korean technology and know-how with cheap North Korean labor. It was the first time that production has been shut down at the complex, the only remaining product of economic cooperation between the two countries that began about a decade ago when relations were much warmer.
Other projects from previous eras of cooperation such as reunions of families separated by war and tours to a scenic North Korean mountain stopped in recent years.
Associated Press writers Hyung-jin Kim in Seoul, South Korea, and Nicole Winfield in Rome contributed to this report.