"Brazil is back!" Lula announced triumphantly two years ago after he unseated far-right incumbent Jair Bolsonaro, who had turned his country into a pariah, to secure a third term as Brazilian president.

The Rio meeting starting Monday is the first of several high-level gatherings that will showcase Brazil's ambition to take a prominent role on everything from climate change to the war in Ukraine. Among them: annual UN climate talks next year which will take place in the Amazon.

Here is a brief look at the diplomatic highs and lows of Lula 3.0 so far:

- Leader on climate -

Lula's biggest diplomatic success has been his leadership in the fight against climate change by overseeing a slowdown in deforestation of the Brazilian Amazon, analysts say.

The annualized rate has fallen to its lowest level in nine years as of end-July 2024, according to the National Institute for Space Research (INPE).

Lula's government has also announced accelerated plans to cut carbon emissions and put forward proposals for a global fund to conserve forests.

The environment is where "has made the most progress," Roberto Goulart Menezes, deputy director of the Institute of International Relations at Brasilia University, told AFP.

Lula's leadership role would likely be strengthened if US President-elect Donald Trump makes good on his vow to again pull the United States out of the Paris Agreement on reducing emissions.

- Bridge-builder -

Lula has long sought to be a builder of bridges between the West and the Global South, earning him the title in 2009 as "the most popular politician on Earth" from then-US president Barack Obama.

His comeback has returned Brazil "to its traditional role, as a trustworthy partner of the international community and a builder of consensus," Foreign Minister Mauro Vieira told AFP.

Part of Lula's pursuit of a multipolar world has boosted Brazil's ties with China -- its biggest trading partner.

A German government source commented that while Lula clearly "represents the interests of emerging markets," he also tries to find common ground with rich countries.

- Prone to 'missteps' -

"It is hard to deny that 'Brazil is back' when compared to the previous administration," Michael Shifter, an expert at the Washington-based Inter-American Dialogue think tank, told AFP.

But Lula has made "some missteps and has been less surefooted in global affairs than he was during his two previous terms in the 2000s," Shifter noted.

Lula drew particular criticism in May 2022 for declaring that Ukraine and Russia shared responsibility for Russia's full-scale invasion of its neighbor launched three months earlier.

The following year he attempted "damage control" by condemning the violation of Ukraine's territory, Shifter said.

But Lula was again accused of pro-Russian bias when China and Brazil in August this year presented a joint roadmap for peace talks between Russia and Ukraine that did not require Russia to surrender Ukrainian territory.

Former Brazilian diplomat Paulo de Almeida said Lula's "anti-Americanism" in part explained his stance on Ukraine as well as his position on Israel's war against Hamas.

Lula has accused Israel of "genocide" in the Gaza -- a position shared by South Africa, among other southern continent heavyweights -- and likened it to the Holocaust. Israel and Brazil have withdrawn their respective ambassadors.

- Eye off Venezuela -

Venezuela is the other weak spot in Lula's diplomacy, experts say.

Lula has taken a tough stance on President Nicolas Maduro, refusing to recognize his widely-rejected claim to have won a third term in July elections. And he has blocked Venezuela's bid to join the BRICS grouping of emerging economies.

But he has not backed the Venezuelan opposition's claim of election fraud nor made strenuous efforts to mediate.

"Venezuela is a lost opportunity for Lula," Shifter said, adding that he "failed to mount a strategy to push for a democratic transition" in the country.

Vieira defended Lula's handling of the crisis, saying "neither Brazil nor the president promise to carry out miracles."