PARIS — Once the fire-breathing leaders of Iran and the United States decide to put their missiles away and talk like adults, France is prepared to act as a broker.

When, or indeed if, that is going to happen is another matter.

At a time when the EU has seemed largely a powerless bystander in a potentially devastating conflict in its neighborhood, France appears to be the only European country ready and able to play a concrete role.

Iran says it has invited France to help with the investigation into the crash of Ukraine International Airlines flight 752, which went down shortly after taking off from Tehran Airport Tuesday night, killing all 176 people on board.

On the night of the crash, Iran launched more than a dozen ballistic missiles at a base in Iraq housing U.S. troops, in retaliation for the killing of General Qassem Soleimani in an American airstrike. Tehran strongly denies that the plane was brought down by an Iranian missile and has said it will not cooperate with U.S. investigators — rebutting an assertion from Canadian Prime Minister Justin Trudeau who said on Thursday that intelligence “indicates that the plane was shot down by an Iranian surface-to-air missile."

The Iranian regime already seems to be engaging in a cover-up or disinformation campaign.

Canada, which had 63 of its citizens on the doomed flight — second in number only to Iran itself — is reeling from the disaster. Three British citizens were also killed and British Prime Minister Boris Johnson quickly backed Trudeau’s statement. In addition, Dutch Foreign Minister Stef Blok, whose country has led the investigation into the 2014 downing of a Malaysian airliner over Ukraine, deemed Trudeau’s assessment "plausible," comparing it to directly to the previous tragedy.

But in a sign of how France views itself not just as able to offer technical expertise, but also as a potential broker of the broader conflict, President Emmanuel Macron has so far refrained from making a similarly definitive statement about the cause of the crash.

In a phone call Thursday, he assured Trudeau that France (where the plane's engines were manufactured) would provide its assistance and knowhow to establish the facts, according to an official in Macron’s office. Other senior French officials also urged that there be no rush to judgment, apparently recognizing the sensitivity of accusing the Iranian military of even inadvertently killing innocent civilians, including 82 of the country's own citizens.

"Before taking a position we need total clarity on what happened and for that there are international investigations that are possible,” Foreign Minister Jean-Yves Le Drian said Friday morning.

But such even-handed caution, while essential to preserving any chance of serving as a diplomatic referee, could also carry significant political risk for Macron. The Iranian regime already seems to be engaging in a cover-up or disinformation campaign.

News reporters who reached the crash site said that nearly all traces of the aircraft have been removed, and Tehran has so far refused to share any information retrieved from the plane’s black boxes.

Adding to the diplomatic sensitivities, France is working, along with the U.K. and Germany, on preserving the Iran nuclear deal — the so-called Joint Comprehensive Plan of Action. U.S. President Donald Trump demanded again on Wednesday that the three European guarantors of the deal abandon it. In the wake of the Soleimani killing, Tehran said it would no longer abide by parts of the deal, although it is still submitting to inspections of its nuclear facilities.

Despite the diplomatic complexity, French officials assert that Macron has a unique position to be able to bring about the deescalation Western allies have been calling for. He has working relationships with both Trump and Iranian President Hassan Rouhani, and the credibility of having laid out, in September 2017, the framework for an expanded Iran deal, including limiting Iran’s ballistic missile program which it used to retaliate against the U.S. on Tuesday.

With more than 1,000 troops on the ground, France is the largest European military presence (along with the U.K.) within the coalition in Iraq and Syria against so-called Islamic State. And the maritime security mission it is putting together is now expected to be operational in February, according to a high-level defense ministry official. A French frigate is already in the zone. A Dutch one is expected to join this month, followed by a Danish one by the fall.

"We are here, we are staying. We stood our ground, and our forces stayed put including when they were at risk in the bases where they are stationed alongside the Americans," the defense ministry official said, in reference to the risk posed by the Iranian missiles.

For all the diplomatic groundwork, the French president faces tough odds in acting as referee in the conflict.

Germany, by contrast, is not participating in the maritime mission and withdrew a quarter of its troops deployed in Iraq in the aftermath of Soleimani's killing.

Both Macron and Le Drian have spoken to a combined two dozen leaders since the United States killed Soleimani. Those include Trump, Rouhani, as well as Russian President Vladimir Putin, Saudi Crown Prince Mohamad bin Salman and Iraqi President Barham Saleh.

But for all the diplomatic groundwork, the French president faces tough odds in acting as referee in the conflict.

Officials still have last September in mind, when Macron came closer than anyone before to brokering the first meeting between U.S. and Iranian presidents in four decades, but failed at the final hurdle.

At the time, the two sides could not agree on whether U.S. sanctions should be lifted before or after the meeting happened, but Trump and Rouhani had each separately agreed to a four-point document Macron had drawn up. It included the lifting of all U.S. sanctions; Iran never acquiring a nuclear weapon; complying with the nuclear deal; and refraining from its regional destabilizing activities.

“Who else can broker de-escalation today? Macron can," said a high-level French diplomatic official, "But he won't spend his political capital if no one wants it."

Despite the cooling of tensions since the Iranian counterstrike, the time may not yet be ripe for a French intervention. "Diplomacy is about keeping channels open, we are doing what we need to," the high-level official added.