President Donald Trump's self-congratulations on Twitter regarding an agreement with Russia for peace in Syria are premature and will likely amount to a mistake, experts and officials say.

The plan for at least a temporary halt to fighting southwest Syria beginning Sunday was announced by Trump and Russian President Vladimir Putin shortly after the pair met for more than two hours at the G-20 summit in Hamburg, Germany, last week. It involves the Jordanian government, centering around a cease-fire covering an incredibly complicated battlefield, where the forces of the Syrian regime backed by Russia continue a war against rebel elements, while the U.S. advances on the Islamic State group strongholds in and around Raqqa. Unpredictable al-Qaida affiliates, Iranian militias and other countries in the region, like Israel , have also complicated the conflict zone in recent months through strikes or attacks .

Initial reports said the cease-fire was holding, even though those familiar with the complex nature of the six-year-old conflict in Syria say it will inevitably collapse. And when it does, Trump's Twitter pledge on Sunday that "many lives can be saved" as a result of making deals with Moscow is also likely come into question.

"Who's party to the cease-fire? Not the jihadists, not al-Qaida nor the Islamic State [group]," says Ryan Crocker, a career diplomat and former ambassador to Syria. "Even if – and it's a big if – those who are party to it want to keep it, it will be sabotaged. No doubt."

Crocker served in Lebanon during the country's 15-year civil war and says the Syrian conflict is far more complicated. This latest cease-fire appears to be wholly a Russian initiative, he adds, providing largely a "big bump" for Putin's attempts to seek international recognition for brokering peace.

"You don't get cease-fires in these kinds of wars that last unless you basically have an overarching political agreement, and we are miles away from that," Crocker says, adding of Trump, "It's going to be another chunk out of his credibility."

Moscow first intervened in Syria in 2015 under the auspices of supporting the government of Bashar Assad with which it has traditionally allied, though analysts believe Moscow's true ambitions centered on securing a place among the top international powers for deciding on Syria's future. Russia continues to maintain an air base and naval station there.

Following Trump's meeting with his Russian counterpart last week – their first face-to-face since he became president – he wrote on Twitter , "We negotiated a ceasefire in parts of Syria which will save lives. Now it is time to move forward in working constructively with Russia!"

The president, whose campaign and presidency is currently under investigation by the FBI, a special prosecutor and Congress for alleged ties to Russia, has repeatedly called for improving relations with Moscow.

Democrats on Capitol Hill, including Rep. Adam Schiff of California, said after the announcement that the cease-fire was a constructive outcome of Trump's meeting with Putin, even if some of the other agreements the leaders made caused alarm among critics and supporters alike.

Sen. Jack Reed of Rhode Island, the ranking member of the powerful Armed Services Committee, said in a statement, "This announcement will be a test of how effectively the Russians can influence both the Syrian and Iranian governments to stop the violence and begin to develop longer-term solutions."

The consequences of that test, however, will likely fall on the U.S. to fix.

"Normally you would say if you make that kind of statement and it fails, it's a pretty big blow to your prestige as a dealmaker. In the case of Trump, it doesn't seem to bother him," says Melvyn Levitsky, a former senior State Department officer for Soviet affairs, now at the University of Michigan's Gerald R. Ford School of Public Policy.

"If the cease-fire fails," he adds," the onus will probably fall on us. The Russians will claim, probably credibly, that they have held their clients to the terms of the cease-fire. … On our side, we have a tenuous hold on the various factions that oppose Assad and some of them, like Jabhat al Nusra, are not under our influence at all."

The latest cease-fire is different than prior agreements brokered under the Barack Obama administration, all of which crumbled within weeks, in that unlike his predecessor Trump has used military force against the Assad regime and its proxy forces.

"It's a huge challenge and not realistic or fair to Trump to expect him to solve immediately what Obama couldn't in six years," says Michael O'Hanlon, a senior fellow at the Brookings Institution. "Much more will be needed than one local cease-fire. But that is at least a beginning."

Others see the cease-fire as a guise, but one the U.S. can help maintain under the auspices of warring parties' not shooting at each other and rallying behind anti-terrorism operations.

"The U.S. has accepted an overarching policy to contain Iran, and that's real, unlike Obama," says James Jeffrey, former ambassador to Turkey and Iraq, now with the Washington Institute for Near East Policy. He points, however, to an absence of a clear strategy for what will happen in Syria and the region after the Islamic State group has been defeated.

"This is a step forward, and he earned this, he earned this by taking the decision to approve the chemical raid," Jeffrey says of Trump, citing the Tomahawk missile strike he approved on a Syrian chemical weapons facility. "But the problem is, what this is going to do is back us into a confrontation with Iran, Syria and Russia. That's going to happen sooner or later."

Trump has also set high expectations with what some former officials consider overly optimistic social media posts.

"To say, 'I've negotiated a peace to end all peaces,' not a good policy. It reminds me a little of 'Mission Accomplished,'" Crocker says, citing President George W. Bush's infamous 2003 proclamation about combat operations in Iraq.