The Yemeni government, in a bid to stem the flow of foreign jihadists, has cracked down on foreign fighters.
But many of those who return are unlikely to be able to find work, with many having been recruited overseas by local fighters.
There are fears that foreign fighters may return to the region in search of work, potentially creating an environment where extremism is amplified.
This could, in turn, make Yemen even more dangerous.
The Houthi-led government is fighting a war against the internationally recognised government in Sanaa, which is backed by Saudi Arabia and its regional allies.
The war has displaced more than 7 million people and killed thousands, and the Houthis are battling for control of the capital.
The Yemen war is the biggest since the 1979 revolution that toppled Yemen’s King Faisal.
The government in Yemen has also struggled to maintain its economic base in the wake of the war.
The country has been plagued by chronic shortages of food and medicine, with most of the country’s electricity generating from oil revenues.
The conflict has also made it difficult for aid agencies to deliver food to needy civilians.
In recent months, the United Nations has been forced to suspend aid deliveries in the country amid a worsening humanitarian crisis.
In an effort to combat the threat of international jihadists, the government in Aden has been cracking down on foreigners and shutting down more than 1,000 suspected foreign fighters, according to the official Saudi Press Agency.
The authorities also arrested dozens of foreigners on charges of having links to Al Qaeda.
The latest round of arrests in Aden comes just a month after the government opened a new consulate in the port city of Taiz, which had been closed since February.
It was the first such foreign-run consulate in Aden since 2014, according the official news agency SPA.
The announcement sparked outrage among the locals, with local officials complaining that the new facility was in direct conflict with the countrys longstanding policies of not allowing foreigners to enter.
The Sanaa-based human rights group Al Arabiya reported that about 300 foreigners had been arrested in Aden in March and April.
“It is a new wave of discrimination against the country,” said Abdul Rahman al-Shabir, a lawyer who works for the group.
“They arrested foreigners for being foreigners, not because of the religion, but because they were not paying taxes.”
The authorities have also closed down a number of social media sites, including Twitter, Facebook and Instagram.
The news agency also reported that the government has shut down the main airport in Sanae, which serves as a hub for foreign fighters heading to Yemen for training.
The Saudi-led coalition has been conducting air raids on the country since March, in what the country says is a campaign against Iran-backed Houthi rebels in the south.
The coalition has accused the rebels of being behind attacks that killed hundreds of civilians and soldiers in Sana’a and in other southern cities, killing thousands more in retaliation.
Saudi Arabia’s government says it is targeting Al Qaeda and other jihadist groups.
In a statement, the country said that the war has resulted in the deaths of more than 5,000 civilians and destroyed about 20,000 homes, while forcing thousands more to flee the country.
Saudi Arabian Foreign Minister Adel al-Jubeir, speaking to the United Arab Emirates’ Al Jazeera television channel, said that Yemen’s security forces are doing their utmost to control the flow from Yemen to other countries.
“The Houthis’ actions in Yemen are against the interests of Yemenis everywhere,” he said.
“We have declared that Yemen is at war and we will fight against them in all its strength, and we call upon the international community to intervene.”
But Yemenis and foreign fighters in the region say they have seen the airstrikes in action.
Ali al-Khair, a journalist and former member of the Yemen opposition, told Al Jazeera that in the past few months he has seen the Saudi-backed coalition conduct bombing raids on areas that are popular with the local population.
“I know many people who have fled to Saudi Arabia to seek refuge,” he added.
“People are fleeing because the war is going on, and they are afraid that the Saudis will start bombing their homes again.”
The Houthis, however, have been unable to take back the territory that they control.
The rebels have been in power since 2014.
In June 2017, the rebels seized control of Sanaa after years of Saudi-funded peace talks between the country and the internationally recognized government in the capital, but have not been able to take over the city.
The peace process has been stalled ever since.
Al Jazeera’s Imran Khan in Riyadh, Saudi Arabia, and Ali Fadel in Taiz contributed to this report.