LIMA, Peru -- President Bush and other world leaders vowed yesterday to act "quickly and decisively" to battle the global economic crisis, as a 21-nation summit predicted worldwide recovery in 18 months.

But the final declaration from the Asia-Pacific Economic Cooperation forum was short on specifics, beyond a vow by participating nations to avoid pressures to implement "protectionist" measures, such as import restrictions.

"We are convinced that we can overcome this crisis in a period of eighteen months," the leaders concluded in a forecast added to a statement originally issued Saturday.

The 18-month time line was reportedly inserted at the insistence of Peruvian President Alan Garcia, who played host to the three-day session of Pacific Rim countries that account for about half of all global economic output. "We are going to defeat this crisis," Mr. Garcia vowed.

But several participants, including Mexican President Felipe Calderon and Canadian Prime Minister Stephen Harper, described the 18-month time line as more of a goal than a prediction.

The summit -- Mr. Bush's final scheduled foreign trip as U.S. leader -- may have been more symbol than substance, analysts agreed. But the forum gave the White House the added support it had sought for its broad guidelines to avert a worsening global economic crisis.

The APEC group strongly backed the so-called "Washington Declaration," a blueprint for economic stimulus and improved regulation hammered out by 20 participating nations earlier this month in the U.S. capital.

"The current global financial crisis is one of the most serious economic challenges we have ever faced," the APEC group said in its concluding statement. "We ... will take all necessary economic and financial measures to resolve this crisis, taking the necessary actions to offer hope to those most in need."

Participating nations such as China, Japan and the United States already have enacted massive economic rescue packages in a bid to limit the fallout from the economic bust.

Earlier, Mr. Bush had urged the Pacific Rim nations to endorse the Washington guidelines, including a commitment to modernizing the traditional watchdog role of governments.

"There's a recognition that, while our economies have changed, the financial structures that we are dealing with were primarily written in the 20th century," Mr. Bush told the APEC forum. "We believe in transparency and integrity in the markets that will make sure that firms and financial products are subject to proper regulation and oversight."

The president's imminent departure from office had a clear effect on the summit's proceedings. President-elect Barack Obama was not represented.

Mr. Calderon warned Mr. Obama against trying to rewrite the North American Free Trade Agreement. Mr. Obama has expressed reservations about the almost-15-year-old trade pact among the United States, Mexico and Canada. Mr. Calderon, a staunch U.S. ally, warned that restricting commerce could spur additional illegal immigration to the United States by shutting down jobs in Mexico.

"The day access is closed," Mr. Calderon told business leaders at the forum, "workers will jump over whatever river or wall you put there."

Participating nations were keen to know what was next from Washington.

"The very understandable concern of these foreign governments is, 'Will the new administration do some sort of policy review?' " Dennis Wilder, the White House's top East Asian adviser, told reporters. " 'Will it try to work with some new ideas?' "