The Obama administration is conducting a final review of its Syria policy as it enters its last hundred days, but the rethink is not expected to lead to any radical changes or significant military interventions that could bring US and Russian forces into head-on confrontation.

The secretary of state, John Kerry, will travel to Lausanne in Switzerland on Saturday to meet the Russian foreign minister, Sergey Lavrov, and their counterparts from the Middle East. Turkey, Saudi Arabia and Qatar are expected to attend. Iran’s participation is in doubt, possibly as a result of the dire state of its relations with Saudi Arabia.

Kerry will brief the UK, French and German governments in London on Sunday, on his way back from Switzerland.

The ministers go into the Lausanne meeting with low expectations, diplomats said. The best of the likely outcomes would be a humanitarian pause in the bombing of eastern Aleppo for two or three days to allow some basic humanitarian supplies to reach the embattled rebel-held districts, home to 275,000 people.

The US state department said Kerry would also use the meeting in Lausanne for side meetings on the mounting civilian death toll from the conflict in Yemen, and in particular the Saudi investigation into the coalition bombing of a funeral hall in Sana’a on Saturday. Human Rights Watch said the bomb used in the airstrike, which killed more than 140 people, was made in the US.

Officials in Washington are downbeat about the chances that such short truces in Syria, even if agreed, will ever be implemented. One European diplomat said Moscow was in no mood for compromise because it felt a military victory was possible.

“They don’t care whatever we say about humanitarian law. Obviously they believe that they can win, that the Syrians can win on the ground. They believe Aleppo can fall,” the diplomat said.

Lavrov said he wanted a smaller meeting in Lausanne to allow for “businesslike” discussions among countries with direct influence on the course of the conflict, rather than the much larger forum of the International Syria Support Group.

Kerry’s flight to Switzerland comes only 12 days after he called an end to bilateral talks with Russia on the Syrian conflict. The state department said it never excluded the possibility of meeting Lavrov in multilateral settings but nevertheless Kerry arrives in Lausanne with little leverage, having admitted to Syrian opposition leaders and allied diplomats that he lost the argument inside the administration for a tougher position towards Russia and its Syrian government ally.

The administration review began with a meeting of top national security and foreign policy officials on 7 October, after it was clear that US-Russian talks on a ceasefire had entirely collapsed. According to Reuters, a second high-level meeting will be held on Friday.

Military options will be included in the review as a matter of course, but any policy likely to bring US and Russian forces into head-on confrontation will almost certainly be discounted. The administration does not see the outcome of the struggle between the Assad regime and the armed opposition as a matter of direct national security. It ranks protecting the US and its allies from terrorism as its first priority in Syria, followed by the destruction or degradation of Islamic State and al-Qaida networks. Supporting the coming offensives on the Isis hubs of Mosul in Iraq and Raqqa in Syria rank higher on the list of priorities than humanitarian relief and the political transition in Syria, according to officials who have been briefed on the policy review.

The most likely outcome of the review is thought to be a new set of sanctions aimed at individuals, ministries and military units deemed to be responsible for the use of bunker-buster and incendiary bombs on residential areas, and the targeting of medical facilities.

However the EU is unlikely to follow the US lead on new sanctions. The renewal of existing sanctions on Russia for its encroachment on Ukraine is due in December and is in doubt at a time when Russian counter-sanctions are affecting some EU member states after an already poor year for agriculture.

“New sanctions? I really don’t feel it on the European side,” the European diplomat said.

The belief in some western capitals that eastern Aleppo will fall by the end of the year was challenged by Charles Lister, a senior fellow at the Middle East Institute in Washington. Lister said the densely populated area could only be captured by ground troops and the Syrian army was too demoralised and disorganised to carry out the offensive, leaving Russia, Iran and the Assad regime to rely on Hezbollah and other Shia militias to do the job.

“Eastern Aleppo is an intensely urban combat environment and if there’s one thing we know about these militia forces, it’s that they have a poor track record of offensive urban warfare operations,” Lister said.

“The key here is how heavily Hezbollah is involved on the ground, as they’re perhaps the only force that has truly demonstrated a capacity for success in urban fighting. The opposition has also planned a substantial counter-offensive on pro-regime lines south-west of the city, as well as other offensives in Hama and Latakia which would seek to draw regime resources away from any Aleppo operation.”

Lister added: “Ultimately, the opposition’s key strengths are its knowledge of eastern Aleppo’s terrain and the regime’s substantial manpower shortage. There’s little doubt that Aleppo will eventually fall should current events continue as they are, but I wouldn’t bet on the battle for the city being quite as quick or easy as the prevailing narrative currently suggests.”

