The aspiring TV journalist had seen members of the militant Islamist group Al Shabab kill some of his closest colleagues.
Now, though two countries away, Al Shabab has pledged to turn even Mr. Yasin's adopted home into a new front line in its battle for Somalia.
Late last month, the militants threatened to attack Uganda's capital, Kampala – along with Burundi's capital city, Bujumbura – after African Union peacekeepers from those two countries allegedly killed dozens of civilians during fighting in Somalia's war-torn capital, Mogadishu.
"I am scared," Yasin says. "I fear that even here in Uganda Al Shabab can attack." Of late, he says he has started receiving anonymous death threats via e-mail.
Threats already against Ethiopia, Kenya
The latest threats to Uganda and Burundi are not the first time Al Shabab has vowed to attack Somalia's regional neighbors. The group has already declared jihad – or holy war – against Ethiopia and threatened to attack Kenya, though has been unable to do anything in either country. Al Shabab may have more capacity to cause trouble in Burundi or Uganadi, since it has dozens of potential havens within the large Somali communities in both nations.
"[Al Shabab does] have the capacity to carry out attacks against Uganda and Burundi, and this threat should be taken seriously," says Paula Roque, a researcher at the Institute for Security Studies in Tshwane (Pretoria), South Africa.
The group is battling the weak transitional government backed by 5,000 African Union troops from Uganda and Burundi.
The key to any attack on foreign soil is the support of radicalized supporters in the Somali diaspora, who are able to get around, identify targets, and handle logistics.
"You have to do a lot of reconnaissance, you have to do indoctrination and recruitment," Ms. Roque says. "It's not an easy thing to pull off. But just because nothing is happening right now, doesn't mean that it can't happen in the future."
'Stepped up our vigilance'
And that's why Ugandan security officials are now watching the ethnic Somalis living in their country to see if they have ties to militants back in Somalia. Additional officers have been deployed around Kampala and plans have been discussed to make all Somalis in the country reregister with the authorities.
"We are not underestimating any threat and have stepped up our vigilance," says Felix Kulayigye, spokesman for the Ugandan Army.
The Ugandan military already knows the brutal power of Al Shabab. In mid-September two suicide bombers killed four Ugandan and 12 Burundian soldiers in revenge for the US killing of a senior Al Qaeda operative in the country.
If many of Kampala's residents are jittery, the atmosphere among the city's 10,000-strong Somali community is like a knife edge. And there are concerns that the vulnerable group could be targeted.
Although he sought to play down Al Shabab's ability to attack Kampala at a hastily convened meeting at the crumbling Somali Embassy in the city, Sayid Ahmed Sheikh Dahir, Somalia's ambassador to Uganda, said that the Islamic militants were trying to drive a wedge between the Somali communities and their host countries.
Just how deep that mistrust already runs was shown recently when – ahead of Al Shabab threats – Ugandan security forces briefly detained and beat Yusuf Mohamed Siad, Somali state minister for defense. The former Islamic militant commander – nicknamed White Eyes – was detained after entering the country without notice and being mistaken for a wanted terrorist.
After sustaining a broken leg in the incident, Mr. Siad was quickly freed.