"Young Saudi protester Ali Mohammed al-Nimr has been executed". This is the news headline we as activists hope we will never read, but the reality is that it could happen at any moment. It has been 11 months since his death sentence was upheld by a Saudi supreme court, and with all legal barriers exhausted there is no further chance of appeal.

Concerns for his life have been further compounded by the start of a new defamatory social media campaign from pro-government Saudi sources, sparking fresh fears that the young protester may be next in line for the executioner's sword.

We know an execution is possible, because it has happened before, only seven months ago. On the 2 January 2016, at the dawn of the new year, the world awoke to horrifying news that peaceful social justice activist Sheikh Nimr al-Nimr, along with a youth protester and three minors, had been executed as part of a mass execution of 47 individuals by the Saudi authorities.

The timing of this execution was strategically calculated, occurring during a global holiday season and followed a lukewarm reaction from the international community to previous media leaks related to news of the sheikh's imminent execution.

"The trumped-up charges levied against my son could only be capable by a trained 'commando', and not by a young teenage boy," said Ali Mohammed's father, Mohammed al-Nimr during a TV interview. Ali Mohammed was violently arrested as a child (age 17) in 2012, in connection with his participation in peaceful Arab spring demonstrations in Saudi's eastern province during 2011-2012.

Months into his detention, during the first official family prison visit, Ali Mohammed's mother described her son's face as "unrecognisable" with clearly visible facial wounds, and during this visit Ali Mohammed complained of torture saying he wished he had died during the first six months of imprisonment. Eventually, Ali Mohammed was brought before the notorious "terrorism court" and sentenced to death in 2014, following an unfair trial based on a coerced confession.

Renewed fears of his imminent execution revolve around recent tweets on Ali Mohammed al-Nimr's case from notorious social media pro-government Twitter account @KSA24, which falsely accuse him of violent crimes, such as the murder of police officers. Such a strategy, suggests the start of a targeted defamatory media campaign to present him as a criminal and build the support and sentiment of the Saudi public for such an execution.

This represents a worrying development, as it mimics a similar defamatory media campaign which targeted Ali Mohammed's uncle, Sheikh al-Nimr, prior to his execution. The very same Twitter account accurately foretold the execution of Sheikh al-Nimr through several tweets in the month leading up to his death. One such tweet published a day before the execution said: "There are only a few hours left until the Iranian proxy is beheaded – Nimr al-Nimr."

Activity from such Twitter accounts should be taken seriously, based on the historical accuracy of past tweets. Such accounts are widely regarded as unofficial devices, used to influence public sentiment and to act as a barometer to gauge public reaction on sensitive issues such as intended executions.

The importance of international support and advocacy cannot be overemphasised. Ali Mohammed al-Nimr remains alive today primarily due to the international outcry in the wake of news of his death sentence conviction being upheld in August 2015. The response was swift and direct: a resolution from the EU parliament to halt the execution, an official statement by UN experts, raising the profile of his case.

Major media outlets picked up the story, and overnight, handsome young Ali Mohammed became the symbolic poster boy emblematic of Saudi's human rights abuses. Online campaigns and petitions ensued. The similar cases of two other Saudi protester minors sentenced to death – Dawood al-Marhoon and Abdullah al-Zaher – were also picked up, prompting further calls to end Saudi child executions, and the launch of online hashtag campaign #FreeThe3.

The worldwide attention that greeted his conviction last year needs to rally once again to stop the execution.

Had it not been for the media and international pressure in late 2015, these three minors would have been executed alongside Sheikh al-Nimr in January 2016. In October 2015, former UK foreign minister Philip Hammond said: "Ali [Mohammed] al-Nimr would not be executed," leading to many breathing a sigh of relief. But be warned, the moment the Saudi authorities sense that public reaction has subsided, they will seize the opportunity to implement the death sentences of these young protesters, all of whom currently remain on death row with no signs of clemency in their cases.

International law prohibit the use of the death penalty against minors. Saudi Arabia officially contended in a 2014 report submitted to the UN that it does not execute minors. In reality this is nothing but PR spin. The 2016 mass execution spree saw the execution of four minors. One of these minors was Ali Saeed al-Rebh, a pro-democracy protester from the eastern province, arrested at the age of 17.

Unfortunately, as al-Rebh's case was not highly publicised, this made it easier for the Saudi authorities to execute him. The other three executed minors were: Mishaal al-Faraj, Amin al-Ghamdi and Mustafa Abkar. Child executions occur despite Saudi Arabia being a state party to the legally binding UN convention on the rights of the child.

Ali Mohammed al-Nimr, Dawood and Abdullah are not alone. European Saudi Organization for Human Rights has documented cases of an additional six minors sentenced to death, indicating that Saudi Arabia, a current member of the UN human rights council, continues to fail in its international human rights obligations.

For now, weekly phone calls and monthly family visits represent the only way to confirm Ali Mohammed al-Nimr remains alive. His family continue to live a daily nightmare, fearing the day they learn of their son's execution via the TV. The worldwide attention that greeted his conviction last year needs to rally once again to stop the execution. But this time our message should not be to merely halt the execution, but the campaign should reconfigurate itself with a stronger message and call for his release. Otherwise, we will witness the illegal execution of yet another al-Nimr.