WASHINGTON, June 17 - When U.S. and Iranian negotiators sit down in Switzerland on Friday after nearly four months of war, the stakes couldn’t be higher as they face an array of hurdles that could derail efforts to reach a comprehensive peace agreement.

While a breakthrough cannot be ruled out, most analysts are skeptical the two sides can forge a final settlement within the 60-day window laid out in a “memorandum of understanding” that President Donald Trump and Iranian leaders approved this week.

That interim pact kicked the hardest issues down the road to the next phase of negotiations, with no guarantee they will ever be resolved. The following are potential spoilers:

CAN THEY CLOSE NUCLEAR GAPS?

The fate of Iran’s nuclear program – which Trump cited as his main reason for going to war - may carry the greatest potential to unravel the talks. Trump has already touted Iran’s commitment never to develop a nuclear weapon, but that largely restates long‑standing pledges by Tehran.

Where the negotiations could falter is over what to do with Iran’s stockpile of near-bomb-grade uranium. Trump has said he wants it shipped out or destroyed. Iran wants neither, though it has indicated a possible willingness to dilute the material.

Another sticking point is Iran’s future uranium enrichment. The U.S. has at times demanded zero enrichment in Iran. Iran says it will not give up its right to enrich. Sources have said the two sides have previously discussed a potential moratorium of anywhere from 5 to 20 years, but compromise remains elusive.

Also in question is whether Iran will accept the level of international inspection conducted under the nuclear deal that former President Barack Obama reached in 2015 and which Trump ditched in 2018.

COULD STRAIT OF HORMUZ COMPLICATE MATTERS?

Questions remain about the strait, which Iran effectively blocked, triggering a global energy supply shock, after the U.S. and Israel attacked on February 28. Under the MOU, the waterway, which normally carries one-fifth of the world's oil, will be reopened on Friday, but shippers remain cautious.

The U.S. says it will be toll-free. Iran, which gained leverage with control of the channel that it lacked pre-war, insists it will retain a management role.

WHAT ABOUT SANCTIONS AND FROZEN ASSETS?

Also standing in the way: Iran wants Trump to quickly lift sanctions and unlock billions in frozen funds, while the U.S. says easing will be gradual and tied to Iranian compliance. According to the text of the MOU read out by U.S. officials on Wednesday, Iran would immediately receive waivers to sell oil again, a conciliatory gesture that has added to criticism from Iran hawks that Trump is giving up too much.

Trump may be reluctant, however, to be seen handing over money to Iran anytime soon. The MOU is already being compared to the deal under Obama, whom he has long berated for returning some Iranian funds.

COULD ISRAEL BE A SPOILER?

Israeli Prime Minister Benjamin Netanyahu, who helped convince Trump to launch the war, has insisted Israel is not bound by any U.S.-Iran agreement in its fight against Iran-aligned Hezbollah in Lebanon.

Though hostilities there have abated since Trump rebuked Netanyahu this week, further escalation could threaten the talks. Iran says the deal also requires a ceasefire in Lebanon.

WILL NEGOTIATING STYLES CLASH?

The U.S. team – Vice President JD Vance, envoy Steve Witkoff and Trump’s son-in-law Jared Kushner – and their Iranian counterparts may have a hard time reconciling disparate negotiating styles.

Trump is known to demand quick results; Iran prefers drawn-out bargaining. This posed a problem in past rounds that ended in failure and could mean a similar outcome this time.

Trump told reporters this stage of negotiations would be “easier” than the first. Both sides are looking to wrap up the conflict. The president is under growing pressure at home over high gasoline prices, and Iran has been battered militarily and economically.

The U.S. team, however, is expected to be short on technical expertise and up against veteran negotiators with a history of dragging out talks. That means 60 days may be too tight to craft a detailed agreement. The Obama deal took around two years to finalize.

Even if a deal is reached, there could be doubts about implementation. Trump helped broker a ceasefire last year in the Israel-Hamas war in Gaza but the process has stalled since then.

COULD DISTRUST BE A FACTOR?

Iran is deeply suspicious of Trump, who twice in the past year attacked in the middle of negotiations.

Whether or not the Iranians are willing to compromise could also hinge on their supreme leader, Ayatollah Mojtaba Khamenei, considered more hardline than his father, who was killed along with the new leader’s mother, wife and son in a U.S.-Israeli strike.

The U.S. will also be distrustful, watching to see if Iran is stringing them along, as Trump aides say they have experienced before.

If they cannot overcome differences to secure a comprehensive settlement, there is still the possibility of a limited agreement or extending talks – though the risk of renewed hostilities would also loom.

OTHER WAYS TALKS COULD FALTER

-- If Trump bows to pressure from Iran hawks to resist concessions, or Iranian hardliners force their negotiators to be more intransigent;

-- If already conflicting interpretations of the MOU create unrealistic expectations;

-- If Trump makes the kind of harsh threats he has issued during the conflict, prompting Iran to break off negotiations. REUTERS

Explainer-What challenges could stand in the way of a final US-Iran deal?