The 24-hour visit by German chancellor Angela Merkel to Israel this week came as relations between the two countries hit rock bottom. According to a report in Der Spiegel magazine last week, Ms Merkel and Israeli prime minister Benjamin Netan­yahu have been drawn into shouting matches when discussing by phone the faltering peace process.

Despite their smiles to the cameras during the visit, tension behind the scenes has been heightened by a diplomatic bust-up earlier this month when Martin Schulz, the president of the European parliament and himself German, gave a speech to the Israeli parliament.

In unprecedented scenes, a group of Israeli legislators heckled Mr Schulz, calling him a “liar”, and then staged a walkout, led by the economics minister Naftali Bennett. Rather than apologising, Mr Netanyahu intervened to lambast Mr Schulz for being misinformed.

Mr Schulz, who, like Ms Merkel, is considered a close friend of Israel, used his speech vehemently to oppose growing calls in Europe for a boycott of Israel. So how did he trigger such opprobrium?

Mr Schulz’s main offence was posing a question: was it true, as he had heard in meetings in the West Bank, that Israelis have access to four times more water than Palestinians? He further upset legislators by gently suggesting that Israel’s blockade of Gaza was preventing economic growth there.

Neither statement should have been in the least controversial. Figures from independent bodies such as the World Bank show Israel, which dominates the local water supplies, allocates per capita about 4.4 times more water to its population than to Palestinians.

Equally, it would be hard to imagine that years of denying goods and materials to Gaza, and blocking exports, have not ravaged its economy. The unemployment rate, for example, has increased 6 per cent, to 38.5 per cent, following Israel’s recent decision to prevent the transfer of construction materials to Gaza’s private sector.

But Israelis rarely hear such facts from their politicians or the media. And few are willing to listen when a rare voice like Mr Schulz’s intervenes. Israelis have grown content to live in a large bubble of denial.

Mr Netantahu and his ministers are making every effort to reinforce that bubble, just as they have tried to shield Israelis from the fact that they live in the Middle East, not Europe, by building walls on every side – both physical and bureaucratic – to exclude Palestinians, Arab neighbours, foreign workers and asylum seekers.

Inside Israel, the government is seeking to silence the few critical voices left. The intimidation was starkly on display last week as the supreme court considered the constitutionality of the recent “boycott law”, which threatens to bankrupt anyone calling for a boycott of either Israel or the settlements.

Tellingly, a lawyer for the government defended its position by arguing that Israel could not afford freedom of expression of the kind enjoyed by countries like the US.

Illustrating the point, uproar greeted the news last month that a civics teacher had responded negatively when asked by pupils whether he thought Israel’s army the most moral in the world. A campaign to sack him has been led by government ministers and his principal, who stated: “There are sacred cows I won’t allow to be slaughtered.”

Similarly, last week it emerged that a Palestinian from East Jerusalem had been interrogated by police for incitement after noting on Facebook that his city was “under occupation”.

Outside Israel, Mr Netanyahu is indulging in more familiar tactics to browbeat critics. Tapping European sensitivities, he accused those who support a boycott of being “classical anti-semites in modern garb”. He justified the allegation, as he has before, on the grounds that Israel is being singled out.

It looks that way to Israelis only because they have singularly insulated themselves from reality.

Western critics focus on Israel because, unlike countries such as North Korea or Iran, Israel has managed to avoid any penalties despite riding roughshod over international norms for decades.

Iran, which is only suspected of secretly developing nuclear weapons, has been enduring years of savage sanctions. Israel, which has hidden its large stockpile of nuclear warheads from international scrutiny since the late 1960s, has enjoyed endless diplomatic cover.

Contrary to Mr Netanyahu’s claim, lots of countries have been singled out by the United States and Europe for sanctions – whether diplomatic, financial or, in the case of Iraq, Libya and Syria, military.

But the antipathy towards Israel has deeper roots still. Israel has not only evaded accountability, it has been handsomely rewarded by the US and Europe for flouting international conventions in its treatment of the Palestinians.

The self-styled global policemen have inadvertently encouraged Israel’s lawbreaking by consistently ignoring its transgressions and continuing with massive aid handouts and preferential trade deals.

Far from judging Israel unfairly, Mr Schulz, Ms Merkel and most other western leaders regularly indulge in special pleading on its behalf. They know about Israel’s ugly occupation but shy away from exercising their powers to help end it.

The reason why popular criticism of Israel is currently galvanising around the boycott movement – what Mr Netanyahu grandly calls “delegitimisation” – is that it offers a way for ordinary Americans and Europeans to distance themselves from their governments’ own complicity in Israel’s crimes.

If Mr Netanyahu has refused to listen to his external critics, western governments have been no less at fault in growing impervious to the groundswell of sentiment at home that expects Israel to be forced to take account of international law.

Both Ms Merkel’s diplomatic niceties and her shouting matches have proven themselves utterly ineffective. It is time for her and her western colleagues to stop talking and to start taking action against Israel.

Jonathan Cook is an independent journalist based in Nazareth