The biggest security operation in Kenya’s history is under way as the vulnerable east African nation prepares to welcome its “son”, Barack Obama, for the first time since he reached the White House.

The US president was due to touch down on Air Force One on Friday evening for a weekend programme in the capital, Nairobi, that includes an international business summit, dinner with his Kenyan counterpart, Uhuru Kenyatta, and a major public address.

Kenya is treating the visit as a chance to shine, akin to an Olympics or a football World Cup, and is all too aware how catastrophic another terrorist attack would be for its image. Three months ago Islamist militants murdered 148 people at a university in Garissa, while an attack on Nairobi’s Westgate shopping mall left at least 67 people dead less than two years ago.

Hundreds of US security personnel have arrived in Kenya in recent weeks and three hotels have been examined by the secret service, according to local media.

Osprey tilt-rotor aircraft, usually stationed at the US military base in Djibouti, flew over Nairobi this week alongside a White Hawk helicopter with presidential insignia, Agence France-Presse reported. Other military helicopters have been flown in reportedly from a US special forces facility at Kenya’s Manda Bay base, from which raids on al-Shabaab militants in Somalia are launched.

“Nairobi is seen as the second most important US embassy in the world after Moscow because of both Somalia and its proximity to the Middle East,” an American source said. “There are so many missions going on that we don’t even hear about.”

Kenya’s civil aviation authority announced that national airspace would be closed for 50 minutes on arrival and 40 minutes on departure, inadvertently revealing the schedule of the president, who will travel without his family.

Obama will then be chauffeured in his bomb-proof limousine, dubbed “the Beast”. The $1.5m (£970,000) car has 20cm-thick steel plates, 13cm-thick bulletproof glass, kevlar-reinforced tyres and a presidential blood bank in the boot.

Around 10,000 police officers – roughly a quarter of the national force – were being deployed in the capital and several major roads would be closed to all but emergency and security vehicles. The move prompted many people to stay at home and numerous banks and schools to shut early on Friday.

Evans Kidero, the governor of Nairobi county, said: “Security is both visible and invisible. It’s something we’ve been working on even before Obama is coming.”

Kidero’s belated attempt to beautify the city by planting grass has been mocked on social media, with Twitter users adopting the hashtag #KideroGrass. “In African culture when you’re receiving an important visitor, when your in-laws are coming, the house must be spruced,” he explained. “Actually we plant grass every year but our people are so indisciplined they walk on them, they kill them. I’m just appealing that they should keep off my grass.”

But security concerns are thought to have played a part in the decision for Obama not to travel to his father’s grave and meet family members in the village of Kogelo. One relative, Said Obama, said: “I would have wished that he visit here but to me the most important fact is he’s coming to Kenya. He’s wearing several hats: he’s a family member and he’s the president of the United States. I know if he doesn’t come to Kogelo, his spirit will be there with us.”

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The 49-year-old half-brother of the president’s father, said Barack Obama senior and junior shared a similar intelligence and deep baritone voice. “I’m feeling proud of Barack,” he said. “He has never failed us. He has put our name on the map.”

Obama himself talked recently about the heavy security restrictions compared with previous trips to his ancestral home, most recently as a senator in 2006. “I will be honest with you, visiting Kenya as a private citizen is probably more meaningful to me than visiting as president, because I can actually get outside of the hotel room or a conference centre,” he said.

The 53-year-old president, who once shot down conspiracy theories that he had actually been born in Kenya by publicly producing his birth certificate from Hawaii, is expected to spend time with family members who will travel to Nairobi, according to White House officials.

Securing the tour is unchartered territory since no sitting US president has previously visited Kenya or Ethiopia, to which Obama flies on Sunday. Both countries are seen as vital allies in the African theatre of the “war on terror”.

At a press conference at Nairobi’s state house, where the Kenyan and US flags currently fly alongside bunting, Kenyatta highlighted the threat. “Our country has endured the attacks of depraved, ideological criminals,” he said. “We have fought them unrelentingly, and they know, as well as we do, that they will lose.”

Kenyatta said there was “very close cooperation” with the US and “the fight against terror will be central” to his scheduled meeting with Obama, who is expected to visit the site of al-Qaida’s 1998 bombing of the US embassy.

But Joseph Nkaissery, the Kenyan interior minister, called on the US-based news channel CNN to apologise for describing east Africa as a “hotbed of terror” during its coverage of the visit. The hashtag #SomeoneTellCNN was trending worldwide as Kenyans condemned the broadcaster.

People have expressed frustration at the zealous security measures but also excitement at the imminent arrival of the world’s most powerful man. Thursday’s Daily Nation newspaper carried the front-page headline, “Son of Kenyan student who changed the world”, and contained a 32-page supplement entitled “Karibu [Welcome] Obama”. Street vendors were hawking American flags, glasses that paired the US flag with Kenya’s and other merchandise.

In a BBC interview on Thursday, Obama justified his visit to Kenya and Ethiopia despite human rights concerns, citing Burma as an example of engagement producing results. Asked about the opposition to gay rights of Kenya’s deputy president, William Ruto, Obama said: “Yeah, well, I disagree with him on that, don’t I?

“Everybody deserves equal treatment in the eyes of the law and the state. And that includes gays, lesbians, transgender persons.”

Obama said he had been blunt with African leaders about gay rights in the past and planned to make it part of his agenda. Kenyatta has described it as a “non-issue” in this weekend’s talks.

Kerry Kennedy, president ofthe Robert F Kennedy Human Rights, said: “It is imperative for President Obama to show solidarity with the brave human rights activists, those who have literally put their lives on the line for the benefit of their countries, during his upcoming visit.

“At a time when the human rights situations in both Kenya and Ethiopia are worsening, the United States government must demonstrate that it stands on the side of the good and the just, signalling that respect for basic human dignity remains at the core of its foreign policy with all nations.”