A propaganda video released by the Somali militant group al-Shabaab, threatening attacks against shopping centres in the west, smacks of a bid to remain relevant as other extremist groups such as Islamic State (Isis) and Boko Haram grab the world’s attention.

The slickly produced 77-minute film, posted online on Saturday, calls for strikes on Oxford Street and two Westfield malls in London, the Mall of America in Minnesota and Canada’s West Edmonton mall. “Westgate was just the beginning,” it proclaims, invoking what might cynically be described as al-Shabaab’s greatest hit: the siege of the Westgate mall in Nairobi, Kenya, in which 67 people were killed by four gunmen.

But that was September 2013 and a great deal has happened since then. Isis has overrun swaths of Iraq and Syria, and produced macabre videos tailored to the modern media cycle. Boko Haram has rampaged through northern Nigeria and stolen headlines with the kidnapping of 276 schoolgirls in Chibok. Islamist gunmen have stunned the world by attacking a satirical magazine in Paris, killing 17 people over three days.

In the perverse battle for eyeballs and retweets, al-Shabaab’s PR department has been outwitted by its murderous rivals, while it has been losing territory after a hammering by American drones and African soldiers. Last September its leader, Ahmed Abdi Godane, was killed in a US air strike, while his successor, Ahmad Umar, has so far failed to establish a similarly high profile. There are two ways for al-Shabaab, an affiliate of al-Qaida, to put itself back on the global agenda. One was seen last Friday with the suicide bombing of a hotel in Mogadishu, killing 25 people, injuring more than 40 and deliberately denting hopes that the capital now has unstoppable momentum with new businesses, a construction boom and a returning diaspora.

The other came a day later: the specific threats to western targets in a video whose style owed something to Isis, according to Anton du Plessis, managing director of the Institute for Security Studies, in South Africa. “They probably feel their profile is significantly slipping,” he says. “It seems to be happening with all the al-Qaida offshoots: they believe that Isis is stealing the limelight with their well-produced videos and slick messaging.”

Boko Haram used “copycat tactics” by declaring an Islamic caliphate in northern Nigeria, he notes, but that option is not open to al-Shabaab following recent setbacks on the battlefield. Du Plessis warns, however, of the continuing potential for lone-wolf attacks. “Although they are on the back foot and have suffered losses, they are still a force to be reckoned with. Nobody knows the extent of their sympathisers in other countries.”

Al-Shabaab has previously carried out attacks in neighbouring Kenya, Uganda and Djibouti, which all contribute troops to the African Union force in Somalia, but it has never operated outside east Africa and the Horn of Africa. But Minnesota, home to the biggest Somali population in the US, has been singled out by terrorist recruiters in the past, according to Associated Press. Since 2007, it said, more than 22 young men from Somali backgrounds in Minnesota have travelled to Somalia to join al-Shabaab, and a handful of Minnesotans have also travelled to Syria to fight within the last year. At least one has died while fighting for Isis.

Cedric Barnes, Horn of Africa project director at the International Crisis Group, says: “This video has a lot to do with recruitment. It is propaganda but it’s also a recruiting tool. There is now competition for radical young Muslims in the west: rather than al-Shabaab, they might go for the immediacy of Isis in Iraq or Syria. There are more rivals than there were.”

Publicly calling for attacks on the west could also be a tactic to put Somalis there under scrutiny by the authorities, Barnes argues, leading to resentment and possible radicalisation among them. In the meantime, US officials said over the weekend there was no credible evidence suggesting a mall attack was imminent.

Stig Jarle Hansen, an academic and author of Al-Shabaab in Somalia, notes that the group have “never staged an attack in a country that was not a part of the African Union forces fighting them. The most likely scenario is that this continues, but al-Shabaab propaganda is professional and it might inspire sympathisers to act.”