The US has dispatched a military plane packed with medical and humanitarian supplies to Somalia, after the top American diplomat in the country declared the bomb attack that killed 300 people met the criteria to “warrant immediate US government assistance”.

With a speed that some will say contrasted with way the Trump administration reacted when a powerful hurricane tore into Puerto Rico, the plane landed in Mogadishu, 48 hours after the massive truck bomb went off, also injuring 400 people. It had flown in from Djibouti.

Scores of people remain missing after the attack and officials said the death toll could still rise, according to the Associated Press.

The US military has dispatched humanitarian aid from its regional hub in Djibouti (AP)

The news agency said in the aftermath of the of blast, which the Somali government has blamed on the al-Shabab extremist group, funerals have continued and dozens of critically injured people have been airlifted to Turkey for treatment.

For the US, the fight against Islamic extremists based in the Horn of Africa has becoming increasingly important. The US military has stepped up the number of drone strikes against al-Shabab, which is also fighting the Somali military and 22,000 African Union forces in the country.

Deadly suicide bombing strikes Somalia's capital

To the north, Djibouti has become host for military bases operated by the US and France, and China has a mounting number of infrastructure projects based there.

Fighting for Freedom in the Somalian drought Show all 18 1 /18 Fighting for Freedom in the Somalian drought Fighting for Freedom in the Somalian drought Zeinab looks after one of her nephews Reuters Fighting for Freedom in the Somalian drought Zeinab's sister Habiba, 29, sits with her children beside their shelter at the camp Reuters Fighting for Freedom in the Somalian drought Zeinab helps her mother and sister build a new shelter Reuters Fighting for Freedom in the Somalian drought Women wait to fill their jerrycans at the camp Reuters Fighting for Freedom in the Somalian drought Zeinab and her sister Habiba carry a jerrycan filled with water to their shelter Reuters Fighting for Freedom in the Somalian drought Zeinab reads an English book in her shelter Reuters Fighting for Freedom in the Somalian drought Zeinab looks in the mirror as she brushes her teeth using a chewing stick Reuters Fighting for Freedom in the Somalian drought Zeinab cleans her feet before going into school Reuters Fighting for Freedom in the Somalian drought Zeinab at the entrance of her classroom near the camp Reuters Fighting for Freedom in the Somalian drought English teacher Abdiweli Mohammed Hersi in the classroom Reuters Fighting for Freedom in the Somalian drought Zeinab applies her make-up before heading to school Reuters Fighting for Freedom in the Somalian drought Zeinab writes in class Reuters Fighting for Freedom in the Somalian drought Zeinab attends a class Reuters Fighting for Freedom in the Somalian drought Zeinab's sister feeds her baby in the camp Reuters Fighting for Freedom in the Somalian drought Abdir observes Zeinab washing dishes as her nephews play REUTERS Fighting for Freedom in the Somalian drought Abdir carries a jerrycan while her daughter Zeinab washes dishes Reuters Fighting for Freedom in the Somalian drought Zeinab outside her shelter in the camp Reuters Fighting for Freedom in the Somalian drought The Hussein family at the camp for internally displaced people in Dolow

For the US, Djibouti is a vital location in a restive region; it is the location of the largest American permanent military base in Africa, Camp Lemonnier, which is home to more than 4,000 personnel. Most of them are part of the Combined Joint Task Force – Horn of Africa.

Al-Shabab has fought in Somalia for more than a decade and has frequently targeted vulnerable locations of the capital, Mogadishu. Earlier this year, it vowed to step up attacks after both the Trump administration and Somalia's recently elected Somali-American president, Mohamed Abdullahi Mohamed, announced new military efforts against the group.

In recent weeks, the Trump administration has been battling criticism over the way it responded to the powerful Hurricane Maria that struck Puerto Rico last month.