Recent videos posted on the internet show Palestinian militants doing target practice with rifles and training to storm buildings while Islamic music plays.
They come from the Gaza Strip, where Islamist groups are committed to armed struggle with Israel.
But the fighters in this footage are different. They joined rebel forces in Syria's civil war.
Earlier this year, Fahd al-Habash from Gaza's Jabalia refugee camp recorded a message asking his family not to mourn him if he died.
"If you hear that I have been killed and left this world, rejoice for me because I got what I wished for," he said.
It is said that soon afterwards the 28-year-old father-of-two was shot dead near Homs.
"My brother never mentioned he was going to Syria," says Shehata al-Habash. "He told us he was going to Turkey to look for a better job."
"I think he always planned to go to fight jihad but he lied so we didn't stop him."
Fahd al-Habash had been avidly following news about Syria and saw it as a just, holy war.
"The situation in Gaza is calm. There's no fighting with Israel right now and Fahd wanted to fight against the Shia [Muslims]," Shehata al-Habash says.
"He saw how [the Syrian President] Bashar al-Assad with [the Lebanese militant group] Hezbollah and Iran were killing people in Syria."
Since the war in Syria started in early 2011, it is estimated that about 30 Palestinian militants from Gaza have headed there.
A veteran militant, Mohammed Qanita, was killed about a year ago after joining the Islamic State of Iraq and the Levant (ISIS), a jihadist group that is linked to al-Qaeda. He had been training new recruits.
The fighter had previously belonged to the armed wing of Hamas, the Izz el-Din al-Qassam Brigades.
In keeping with the popular mood, Hamas celebrated him as a "martyr" after news emerged of his death.
Yet the Islamist group, which governs Gaza, had been trying to distance itself from involvement in the Syrian conflict.
Its early support for Sunni Muslim rebels fighting President Assad put a heavy strain on relations with Tehran, a key ally of Damascus.
The movement's exiled leadership, which used to be based in the Syrian capital, was forced to leave and Iranian funding for Hamas was cut.
In Beit Hanoun in northern Gaza, Jihad al-Zaanin says his son was only able to leave for Syria in June after convincing the authorities that he was just making a pilgrimage to Saudi Arabia.
"Mohammed insisted he wanted to go to Mecca. That was his dream so what could I do to stop him?" asks Jihad. "Everything for him was about religion and he chose his path. He chose martyrdom."
The university student, who had been a member of a Salafist Islamist group in Gaza, also joined ISIS in Syria. He is said to have blown himself up in a suicide attack.
Fleeing to Gaza
However the movement between Gaza and Syria is not just in one direction.
Dozens of Syrian refugees have headed here since the war started, as well as hundreds of Palestinian refugees who were living in Syria.
At the new Damascene restaurant in Gaza City, a Syrian chef is kneading dough by a wood stove to make traditional snacks. He set up his business with a long-time Palestinian friend.
Before the war, about half a million Palestinians lived in Syria. They or their families fled or were forced out of their homes in the 1948 war that followed the creation of Israel and the 1967 Middle East war.
Hamza Issa was brought up in Yarmouk refugee camp on the edge of Damascus but decided to leave for Gaza a few months ago.
"I came here directly because Gaza is my homeland. It was the obvious choice because I am Palestinian," he says.
"We used to have a good life in Syria. We were treated as well as citizens. But now a lot of people have been killed - even some of my friends. The situation was chaotic, that's why I left. There's no work there and you can't study. It's terrible."
The United Nations agency for Palestinian refugees, UNRWA, says that fighting between government and opposition forces has driven away most of the 150,000 Palestinians who lived in Yarmouk camp.
"The Syria crisis continues to have a devastating impact on the Palestine refugee community, which must not be forgotten," says UNRWA spokesman Chris Gunness.
"Continued military escalation is exacerbating the suffering of ordinary Syrians and Palestinians alike."
UNRWA is now supporting 1,000 Palestinian refugees from Syria in the Gaza Strip. They are entitled to the same benefits and services as refugees who were already based in Gaza.
However, recent arrivals have found out fast that Gaza is a tough place to live.
There are high rates of poverty and unemployment in the small, overcrowded coastal strip.
Tight border restrictions are imposed by Israel and Egypt. In the past five years residents of the Palestinian territory have endured two short but intense conflicts with Israel.
A kebab shop manager, Ahmed, came with his wife and son from Deraa in southern Syria to seek refuge in Gaza. They made their way here from Egypt via tunnels that have since been shut down.
"The situation was very dangerous at home. We escaped shelling and clashes," says Ahmed. "In Egypt I met a man from Gaza and we decided to open the Syria House restaurant here."
"Syrian and Palestinian culture and traditions are quite similar but it was difficult here at the beginning," he goes on.
"Thanks to God they are now giving us help. Recently the Hamas Prime Minister gave each family US$500 and promised houses, jobs and free education for our children as well as health insurance."
Despite the upheaval, Ahmed counts himself lucky to have escaped the war. "Gaza is safer than Syria for now," he says.
However he admits that the future here also feels uncertain, adding: "Whatever happens to the people of Gaza will now happen to us too."