On Friday, President Obama arrived in Kenya, the birthplace of his late father, for his first official visit to the east African country.

Obama, at the start of a planned three-day visit, was greeted on the tarmac in Nairobi by President Uhuru Kenyatta and other top Kenyan officials, and he received a hug from his half-sister, Auma Obama.

Forging closer trade ties with Kenya is a key item on the agenda for Obama's visit. Also likely to figure in discussions is the battle against the Somali-based, al-Qaida-linked al-Shabab extremist group, which has carried out attacks in Kenya, most notably a 2013 assault on a shopping center in the capital that resulted in the deaths of at least 67 people and an attack on a Kenyan university that killed 148 people.

Ahead of his fourth visit to Africa since taking office — the most for any sitting U.S. president — Obama spoke of the continent's hope and difficulties.

"Despite its many challenges — and we have to be clear-eyed about all the challenges that the continent still faces — Africa is a place of incredible dynamism, some of the fastest-growing markets in the world, extraordinary people, extraordinary resilience," Obama said, adding that he believes Africa "has the potential to be the next center of global economic growth."

As NPR's Gregory Warner says, Obama's mission "is to change the image of Africa in the West to encourage investment in fast-growing African economies without seeming to legitimize African leaders."

As The Hill notes, for Obama the trip "will bring into sharp focus his relationship with Barack Obama Sr. — a complicated man who Obama barely knew."

According to Reuters: "Hours before Obama's arrival, police blocked major roads and emptied streets of traffic in the usually congested capital as part of a huge security operation. In the darkness, excited Kenyans lined parts of the route to his hotel, cheering as Obama's cavalcade passed by."

USA Today described the capital as being "on lockdown":

"While his arrival is heavily anticipated because of his Kenyan roots, many in this capital city are already chafing under the tight security measures meant to reduce crime and minimize terrorist threats."Vendors can't sell trinkets, families can't buy vegetables and residents can't withdraw cash from banks. The government has told non-essential businesses in Nairobi to close and residents to stay home until Obama leaves Sunday for Ethiopia."Copyright 2016 NPR. To see more, visit http://www.npr.org/.