Cabo San Lucas, Mexico ? United in a common mission, leaders of nations and corporations tackled an urgent global dilemma Thursday: how to open borders to trade while closing them to terrorists. But violence kept Russia’s president away as his Pacific Rim counterparts streamed in for a weekend summit.

The parallel gatherings of ministers from four continents and executives from 400 companies as well as the violence that has hit nations of the Asia-Pacific Economic Cooperation forum left no doubt that the realms of finance and diplomacy have merged. In the post-Sept. 11 world, terrorism sends markets plunging, and the global economic slump forces politicians to rethink priorities.

“You can’t trade in an insecure world,” said Nelson Cunningham, managing director of Kissinger McLarty Associates, a Washington consulting firm. “APEC has been hijacked by the terrorists.”

Secretary of State Colin Powell said APEC members would soon launch “a package of bold joint actions to make the flow of trade, finance and communication more secure.”

Heads of state began arriving Thursday for the culmination of the conference, a weekend summit where war in Iraq, nuclear weapons in North Korea and guerrillas in Russia will be as frequent topics of conversation as free trade and economic recovery. The first to arrive was South Korean President Kim Dae-jung, who descended the stairs of a Boeing 747 with a wave and a smile.

The ministers made clear that in a world where terrorism strikes commerce as hard as it does flesh and blood, the two topics cannot be separated.

“If we can’t move goods and people, we can’t trade in a global economy,” said Thomas Donohue, president of the U.S. Chamber of Commerce.