The World Court's ruling April 20 faulted Uruguay for failing to consult with Argentina before building the eucalyptus pulp mill with Finnish help, but rejected Buenos Aires' demand for relocating the plant away from the river on the Uruguay-Argentina border.
The judgment was celebrated as a victory for both sides -- perhaps too soon. Protesting pickets blockading a bridge that links the countries refused to accept a summary end to their cause and vowed to carry on.
Pickets have blocked access on the bridge since 2006, when the pulp mill opened, forcing travelers between the two countries to use boats instead.
Argentine government appeals to the protesters last week went unheeded. Ignoring the court's ruling the plant doesn't pollute the river, campaigners said they won't withdraw until the plant is moved.
Argentine environmentalists backed the pickets, to the dismay of outside observers who hoped the court's ruling that no pollution was taking place would calm the protesters.
Instead, the weekend protests turned out to be larger than expected and activists carrying Argentine and Uruguayan flags thronged at the bridge.
The protesters offered prayers and chanted Argentine and Uruguayan national anthems -- a further indication that early resumption of trade and traffic between the border cities of Gualeguaychu in Argentina and Fray Bentos in Uruguay was still a distant possibility.
Argentine activist and Assembly member Jose Pouler repeated demands for the plant's closure and relocation to ensure a healthy environment for local residents.
He called Uruguay's armed guard on its side of the bridge a provocation.
This week Uruguayan President Jose Mujica will visit Buenos Aires again for talks with Fernandez to help defuse the situation.
Argentina wants joint monitoring of the pulp mill's activities and their impact on the river water and air quality.
Last year's election of Mujica, a former left-wing guerrilla fighter, and his conciliatory approach to the problem diluted a belligerent campaign that had won Fernandez popular support and fanned anti-Uruguay sentiment.
But Argentina went ahead with the International Court hearing, despite signs that Mujica's inauguration in March as president had turned international opinion in Uruguay's favor. Independent assessments contradicting Argentina's claim that the mill was polluting the river also led to critics calling on Fernandez to drop the case and opt instead for direct talks.
After the ruling Fernandez scaled down the rhetoric, vowing to resolve the dispute through negotiations. Asked about the court judgment Mujica told the media, "The only words are silence and there's much work ahead."
Analysts said Argentina will need to try a series of face-saving gestures and work with Mujica to persuade the protesters to leave the bridge.
Uruguayan government officials said they hoped the episode could be put aside and closer collaboration with Argentina could resume.