Improvement in aviation safety and the security situation in Somalia prompted foreign airlines to launch flights.
The U.S. State Department confirmed at least one American was among those killed in the attack.
The four were joined in their criticism of Trump by top Democrats in the House of Representatives.
In 2013, he refused to swipe t-shirts with an Israeli player in a display of support for Palestinian rights.
The western countries begin to establish diplomatic missions in the war-torn nation.
At the weekend, Guinea president responded by saying Somaliland had all rights to chart her destiny.