Bomb-sniffing dogs are on patrol and thousands of cops roam the streets here to control the hordes of protesters gathering for the forum Friday and Saturday of 21 leaders of the member "economies," as they are officially called, of the Asia Pacific Economic Cooperation group.
For all the apprehension, however, this hustling port city on the Korean peninsula's southeastern coast is irrepressibly proud of its role in hosting APEC, along with 10,000 foreign officials and journalists. Many dismiss the demonstrators as aberrations in a mercantile community of more than 4 million people at the heart of the industrialized southeastern corner of South Korea.
"Don't pay attention to them," says Jung Won Bok, a retired Army officer, chatting in a district of flashing neon signs. Gantry cranes above cargo containers stacked nearby make this port one of the world's 10th largest. "They are only a small minority."
In fact, thousands of protesters from throughout Korea are converging here - workers wearing red headbands identifying them as members of the powerful Korean Confederation of Trade Unions to farmers crusading against legislation designed to open markets gradually to competition from imported rice and other products.
Placards and banners denouncing President Bush and US forces as well as APEC are more than matched, however, by signs above doorways, in windows, and strung across streets welcoming APEC. Many see the meeting as a boon to the prestige of a city that rivals Seoul as a commercial center and far outstrips Korea's second-largest port, Incheon, 20 miles west of Seoul, as a conduit for Korea's booming trade.
In advance of the APEC gathering, Bush and South Korean President Roh Moo-hyun met Thursday in Gyeongju, the ancient capital of Korea. A central topic was the nuclear standoff with North Korea.
A day earlier, a senior foreign ministry official spoke confidently of the rapport between the US and South Korea on the issue, despite having held distinctly different viewpoints.
"There is no difference between the Republic of Korea and the United States," on North Korea, said Kim Suk, director-general of the North American desk of the foreign ministry.
"We had close cooperation," he added, at the latest six-party talks in Beijing that wound up last week with North Korea and the United States basically restating their long-held positions.
North Korea demands that the United States provide a light-water nuclear energy reactor and other forms of aid before abandoning its nuclear weapons, while the United States insists North Korea give up its weapons before aid kicks in.
After their meeting, Bush and Roh declared that a nuclear-armed North Korea "will not be tolerated." They also agreed that the standoff with the isolated nation should be resolved through peaceful diplomacy.
Thursday, as Pusan prepared for Friday's APEC beginning, the dominant mood was upbeat, crossing generations and backgrounds.
"We are very proud of APEC," says Kim Hyo-Jung, a student at a local college. "It is a great occasion, and it is good for Pusan."
Ms. Kim, like Mr. Jung, dismisses the outcries of radical politicians and student organizations as representing "only a small group" and confidently predicts that the police on the streets, reinforced by fighter jets and helicopters above and naval vessels lurking just outside the harbor, will guarantee, "Everyone will be safe, and nothing will happen."
If such optimism is rife at Bexco, the acronym by which the Busan Exhibition and Convention Center is known, it hardly represents the view of intelligence officials as they gird for a wide range of scenarios on the eve of the APEC gathering.
"Since we are a free democracy, it is not possible for us to completely block out protests and rallies," says a senior official.
People here agree the meeting will boost the image of Pusan but is likely to end the bridge on the benefits of free trade.
Kim, the student, is philosophical. "I agree with the position of the farmers," she says, wondering how they can get along if rice pours in unchecked, "but we have to accept the global situation."