South Africa's decision to distinguish between imports from Israel and the territory it controls beyond the 1948 borders is a challenge that the Netanyahu government will find hard to ignore.
Last week, Pretoria required goods produced in the Occupied Territories to be labelled as such, "to prevent consumers being led to believe that such goods come from Israel", Jimmy Manyi, the cabinet spokesman announced.
"This is in line with South Africa's stance that recognises the 1948 borders delineated by the United Nations, and does not recognise occupied territories beyond these borders as being part of the state of Israel."
Given its physical and historical remoteness from the Middle East, South Africa's opinion on the issue might hardly matter. Yet, judging from the Israeli response, it clearly does.
South Africa is, of course the original "apartheid state". It also made the transition to democracy in a relatively peaceful manner and saw an all-white Afrikaner nationalist ruling party hand power to a black government voted in by popular majority.
Late last year, the London-based Russel Tribunal held in Cape Town declared Israel an apartheid state; South Africa also hosted the Durban racism conference in 2001, from which Israel, the US and other countries withdrew when protesters turned Zionism into the main issue of the event.
South Africa's transition to equality was capped by the victors' choice not to retaliate against former oppressors, with Nelson Mandela going so far as to take tea with Percy Yutar, the prosecutor who presented faked evidence in Mr Mandela's treason trial in an attempt to secure the death penalty. As it turned out, Mr Mandela was "only" sentenced to life in prison, of which he served 27 years.
Jews served in significant numbers in the underground liberation movements, including the man who now leads the trade and industry ministry, Rob Davies. He was forced to flee the country in the late 1970s because of his anti-apartheid activities. It was Mr Davies's department that oversaw the drawing up and execution of the labelling law. There's no question it would not have come into being without his explicit support.
Mr Davies was by no means an isolated example of Jewish anti-apartheid activism. Before his final arrest, Mr Mandela hid out on properties owned by prominent Jewish families who felt that they could not be part of an oppressive system.
It is this combination of an ethical challenge from venerable elements in an established Jewish community, and the country's history in transcending racial inequality, that landed a powerful blow in this recent decision.
This is something Israel can hardly ignore, and indeed it has not. South Africa's ambassador was summoned for a dressing down by the Israeli foreign ministry. The issue has also excited vigorous discussion in the Israeli press.
Israel's Deputy Foreign Minister Danny Ayalon responded with a statement that to most South Africans was wildly offensive: "South Africa remains an apartheid state."
But perhaps the best summation of the labelling decision's effect was by columnist Bradley Burston for Haaretz, the left-wing Israeli daily, titled South Africa is right. Labelling Israeli settler products is truth in advertising.
Burston wrote: "The decision to label products from the territories strikes with elegant nonviolence at the Netanyahu government's single most cherished goal - obliterating for all time the Green Line border, which demarcates the occupation."
The implications are clear, and others are sure to follow. Although the EU has crimped tax-exempt status for settler-produced imports, South Africa is the first country to specifically label imports from across Israel's blurred border as from "occupied" territory.
In doing so, it sets an international standard to challenge the fiction that Israel's borders are as yet undetermined and a matter for debate. It's a benchmark that will doubtless gain traction. At the very least it will give impetus to the Irish deputy prime minister Eamon Gilmore's suggestion earlier this year that Ireland might push for goods from settlements to be banned from the EU.
The labelling issue may have little material effect in itself, but it does threaten to rob the Israeli government of the control of its narrative relating to the occupied territories. The vociferous response showed that Israel understands this very well.
For its part, South Africa can expect some bruising in the international arena. Its diplomats have been warned that the country is meddling in terrain in which it has no business. Pointed remarks about South Africa's many problems are raised as a reminder that it should stick to its own sphere.
In the same breath that he called South Africa an "apartheid state", Mr Ayalon also referred to the recent shooting of 34 mineworkers by a squad of panicked, badly trained policeman during a labour dispute, implying the country should attend to its own issues.
He may have a point, but there's no denying South Africa's gesture has laid down a line that the Netanyahu administration will find hard to erase.
Gavin du Venage is a business journalist and commodities analyst based in South Africa