From Washington, this is VOA news. I'm David DeForest reporting.

Rebel factions in Syria are expressing a number of reservations about the terms of a U.S.-Russian agreement that will usher in a cease-fire.

The Free Syrian Army group wrote to the United States, saying the cessation of hostilities would primarily benefit the government of President Bashar al-Assad.

In an apparent bid to strengthen their positions ahead of the stop in fighting, government and rebel troops fought in several parts of Syria Sunday. Airstrikes on the city of Aleppo just ahead of the cease-fire killed a number of civilians.

The United States Sunday marked the 15th anniversary of the 2001 terrorist attacks.

President Barack Obama observed a moment of silence at the White House and spoke at the Pentagon.

"We run our fingers over the names in memorial benches here at the Pentagon. We walk the hallowed grounds of a Pennsylvania field. We look up at a gleaming tower that pierces the New York City skyline. But in the end, the most enduring memorial to those we lost is ensuring the America that we continue to be."

The country's major presidential candidates, Donald Trump and Hillary Clinton, paid their respects at Ground Zero.

Hillary Clinton's doctor says she has been diagnosed with pneumonia but is recovering nicely. Clinton abruptly left the 9/11 ceremony in New York because she was not feeling well.

The video shows Clinton stumbling off a street curb, her knees buckling as aides helped her into a van.

Dr. Lisa Bardack says the 68-year-old Clinton's unsteadiness was caused by being overheated and dehydrated. The doctor examined her Friday for a prolonged cough.

This is VOA news.

Police in France have thwarted a possible terrorist attack in Paris this weekend by arresting a 15-year-old boy suspected of planning an imminent "violent action."

The arrest of the teenager Saturday came two days after police moved in on what the Paris prosecutor says was a group of female "commandos" arrested after an aborted attack at Notre Dame Cathedral and another possible attack.

Intelligence agents suspected the boy planned to carry out a knife attack in a public place, but officials refused to name the spot where the attack might occur.

An initial poll in Croatia's parliamentary election Sunday indicates that the left-leaning Social Democrats and their People's Coalition were in the lead, but there was not a clear winner.

According to the poll, the People's Coalition won 58 seats in Croatia's 151-seat parliament. The conservative Croatian Democratic Union won 57 seats. MOST won 11 seats.

This latest election was second time in less than a year that Croatia held an election just one day after parliament was formally dissolved.

Hundreds of thousands of Catalans marched in Barcelona and other Spanish cities on Sunday, rallying for independence.

Catalan police say as many as 800,000 marchers turned out while the Spanish government says the turnout was less than half that number.

Calatonia's pro-independence regional government has set the middle of next year as a target for independence from Spain, but has been unable to persuade the central government to approve a referendum on the issue.

Leading proponents of Brattain's leaving the European Union formed a new pressure group Sunday called Change Britain. The group aims to help "deliver the UK's referendum result in the most effective way."

Opponents of Brexit have warned that leaving the bloc would lead to economic peril. But the country's economy appears to have performed strongly in the 78 days since the vote, undermining predictions of gloom and doom.

And now, leading Brexiters are calling more loudly for a quick, sharp break with the EU, or a "hard Brexit" as it's called.

Fighting between police and protesters erupted in southeastern Turkey after a government announcement that it had replaced 28 elected municipal and district mayors in several predominantly Kurdish towns.

The Turkish Interior Ministry said Sunday that the removed officials are suspected of having ties with what the government considers terrorists.

The most important day in the annual five-day Hajj was celebrated by nearly 2 million Muslims Sunday in Saudi Arabia.

Muslims gathered beginning at sunrise on Sunday at what is known as Mount Arafat. It's about 15 kilometers from the city Mecca.

In Washington, I'm David DeForest.

That's the latest world news from VOA.