When WikiLeaks whistleblowers began circulating in April footage of a 2007 Iraq war incursion in which US military personnel unwittingly killed two war correspondents and several civilians, the international community was aghast at the apparent murder. With sobering questions on the material's full context largely falling on deaf ears, the group was free to editorialise the scene as it pleased: "collateral murder".

But now, with the recent release of sensitive diplomatic cables, WikiLeaks may have committed its own collateral murder, upending the precarious balance of power in a fragile African state and signing the death warrant of its pro-western premier [see also: Wikileaks, Morgan Tsvangerai and the Guardian].

Zimbabwe's Morgan Tsvangirai's call to public service has been a tortured one, punctuated by death and indignity.

His numerous arrests and brushes with death began in 1997, when he emerged as the unlikely face of opposition to President Robert Mugabe. That year, Mugabe's henchmen nearly threw Tsvangirai from the window of his tenth floor office. He would be arrested on four separate occasions in the years to follow. During one such arrest, in 2007, he was severely beaten and tortured by Zimbabwean special forces at the behest of the ruling political party.

After Zimbabwe's 2008 presidential contest – featuring incumbent Mugabe, Tsvangirai and independent Simba Makoni – failed to award any candidate with the majority necessary to claim victory, the election defaulted to a runoff between the two highest vote-getters, Mugabe and Tsvangirai.

In the days succeeding the first round of balloting, Tsvangirai was the alleged target of an assassination plot and subsequently taken into the custody of Mugabe's police, for which American and German diplomats demanded his immediate release. After initially committing to pursuing a second challenge to Mugabe, Tsvangirai withdrew in protest, lambasting the election as a "violent sham" in which his supporters were risking their lives to cast ballots in his favour. Indeed, it is estimated that over 100 MDC supporters met an untimely demise in the period following the election.

Following intense negotiations, the two parties agreed in February 2009 to a coalition government, in which Mugabe would remain head of state – a post he had held uninterrupted for 30 years – and Tsvangirai would assume the premiership. Not one month later, Tsvangirai and his wife were involved in a suspicious collision with a lorry. Though the prime minister survived, his wife for 31 years died.

The Guardian last week published a classified US state department cable relating a 2009 meeting between Tsvangirai and American and European ambassadors, whose countries imposed travel sanctions and asset freezes on Mugabe and his top political lieutenants on the eve of Zimbabwe's 2002 presidential election. Though western sanctions don't prohibit foreign trade and investment or affect international aid – it's said that Zimbabwe's 2009 cholera epidemic topped 100,000 cases, registering some 4,300 deaths – the Mugabe administration effectively characterised the sanctions as an affront to the common Zimbabwean, further crippling the nation's already hobbled economy. (Zimbabwe's national unemployment figure hovers somewhere near 90%.)

Publicly, Tsvangirai opposed the measures out of political necessity. In private conversations with western diplomats, however, the ascendant Tsvangirai praised its utility in forcing Mugabe's hand in the new unity government.

Now, in the wake of the WikiLeaks' release, one of the men targeted by US and EU travel and asset freezes, Mugabe's appointed attorney general, has launched a probe to investigate Tsvangirai's involvement in sustained western sanctions. If found guilty, Tsvangirai will face the death penalty.

And so, where Mugabe's strong-arming, torture and assassination attempts have failed to eliminate the leading figure of Zimbabwe's democratic opposition, WikiLeaks may yet succeed. Twenty years of sacrifice and suffering by Tsvangirai all for naught, as WikiLeaks risks "collateral murder" in the name of transparency.

Before more political carnage is wrought and more blood spilled – in Africa and elsewhere, with special concern for those US-sympathising Afghans fingered in its last war document dump – WikiLeaks ought to leave international relations to those who understand it – at least to those who understand the value of a life.

• This article was amended on 11 January 2011 to clarify the fact that the 2009 cable referred to in this article was placed in the public domain by the Guardian, and not as originally implied by WikiLeaks. The photo caption was also amended to reflect this fact