Peru's President Alberto Fujimoro went on television in Lima to announce saturation bombing of an Ecuadorean position by 16 warplanes in preparation for a "final assault".
Officials of the US, Argentina, Brazil and Chile huddled in the Brazilian capital, a week after earlier attempts in Rio de Janeiro failed to silence the guns. The four nations are "guarantor powers" of the 1942 Rio protocol that followed an earlier Peru/Ecuador war and marked out most of the border.
Military attachs say fighting is heating up, with an estimated 200 soldiers and civilians dead and a similar number wounded in two weeks of conflict. Despite having three times the military might of Ecuador, Peru has been unable to dislodge Ecuadorean forces from key heights at Tiwintza in a 48-mile stretch of disputed territory.
Ecuador seems well prepared for the latest flare-up, with its troops dug in among the heights, too high to be targeted by Peru's artillery and well-positioned to shoot at Peruvian helicopters. Ecuador said it shot down a fourth helicopter on Wednesday, while Peru said it had suffered an "accident" and that its three-man crew was missing.
Two months before he stands in presidential elections, President Fujimori appears determined to dislodge the Ecuadoreans as passions have increased on both sides. What is worrying Latin Americans is the cost of all-out war and its domino effect on investment.
Economists estimate each side is already spending around $10m (£6.6m) a day on the conflict and that an officially declared war would devastate their economies. Ecuador has already announced emergency measures, including rises in VAT and highway taxes as well as cutting the salaries of state workers. Peru may do the same.
Amazon Indians and environmentalists say the conflict is already devastating the lives of thousands of Indians, some of whom have been recruited to fight for either side. Others have been killed while several thousand have fled their communities and are wandering the jungle without food.
There have been reports in Ecuador of Peru using Indian soldiers as "cannon fodder". Television footage shows a high proportion of indigenous troops on both sides.
"The Shuar and other indigenous communities are on the verge of extinction," said Rafael Pandam, himself a Shuar and vice-president of the Confederation of Indigenous Nationalities of Ecuador. He said 10 of his relatives had been recruited to fight for Ecuador as part of indigenous patrols known as the Demons of the Amazon. "But on the other side, there are also Shuar and other natives at the front. We should not be killing our own indigenous brothers across a frontier that for us does not exist in this our original homeland."