It really should come as no surprise. All the factors are there, and they are known. Anyone who follows the Palestinian issue knows that the Israeli government is currently obsessed with BDS, the worldwide movement for Boycott, Divestment and Sanctions against Israel.

The Israelis themselves have made it clear that international "de-legitimisation" constitutes the greatest threat to their state, as currently constituted, and they're hardly taking it lying down. And the fact that Israel has a potent international lobbying capacity, particularly in the US and the UK, through which the Israelis have long employed foreign organisations to leverage and enhance their influence in key foreign capitals, is hardly a secret.

And yet … and yet, Al Jazeera's undercover investigation of Israel's anti-BDS covert influence campaign in the UK still manages to shock.

READ MORE: Everything you need to know about the BDS movement

The shock I have in mind, though, is one which gradually grows in the mind of the viewer. It is not what one would think - the scandal on which the British press and a number of prominent political figures are focused, albeit with good reason.

Yes, the idea that a representative of a friendly power would express willingness to support an effort to "take down" a British government politician whose views are deemed inconvenient to Israel is the stuff of classic hostile espionage, and an easy outrage upon which to focus.

Is this legitimate?

But the real, pervasive scandal here is far more subtle, and its gradual, inexorable revelation is where the true value of this Al Jazeera investigation lies.

The power of this expose resides in the fact that it forces one - even one who might otherwise be inclined to a sympathetic view of Israel - to ask, again and again: Is this legitimate? Lobbying and persuasion we are all used to. But when does that effort go too far? Where are the boundaries? And when are those boundaries crossed simply in virtue of the fact that the ultimate sponsor of the views expressed, or of the individuals expressing them, or of the organisations to which those individuals belong, is a foreign power? Blackmail and political subversion are clear enough: It is the insidious threats that are more to be feared.

READ MORE: Israel's parliamentary plot against UK politicians

It may be one thing for Mr Shai Masot, an official of the Israeli embassy in London, to seek out young British citizens inclined to support Israel. They are hardly being coerced. But do we begin to feel our perceptions change when it turns out that such young political activists are being systematically provided with jobs at the Israeli embassy as part of their vetting process? Or that they are then being placed in organisations which benefit from unacknowledged Israeli cash? Or that the ostensibly organic activities of a number of these organisations are in fact being coordinated under the auspices of a foreign embassy?

These are not the sort of questions which normally occur to ordinary citizens of open societies. And the answers, absent real thought, might not be obvious either. The fact that Mr Masot, the Israeli operative, is so careful to ensure that Israeli fingerprints are kept hidden, and that his own role, beyond that of an overt advocate for Israel, is both discreet and deniable, may give us a hint - as does the rather unseemly haste with which Mark Regev, the Israeli ambassador to Britain, has of late disavowed Mr Masot's activities.

As a former professional intelligence officer, and one who grew up during the Cold War years of zero-sum global competition for influence between the United States and the Soviet Union, I think there is much that is familiar in the Israeli activities revealed by Al Jazeera.

The writer can vividly recall an instance in which he was briefing a hostile member of the US Congress - one inclined to the view that US activities abroad should always conform to the transparency which normally characterises government activities at home - concerning a proposed foreign influence operation which would have required presidential approval.

The contemplated activities were remarkably similar to those being sponsored as we speak by the state of Israel - in the UK and, we must assume, in many other places as well. It would be fair to say that my congressional friend and I approached the matter of covert influence abroad with different sets of assumptions.

Will we sleep on?

It was only after some time, and with considerable frustration, that the American tribune of the people put the question directly: Would what I proposed to do violate the law if practised in the US? The response was "no" but with a major caveat: These activities would be perfectly legal if openly performed by legitimate entities in the US, but would be thoroughly illegal if promoted in secrecy by a foreign power. And therein lay the critical difference.

If there is shame here, it is not with those playing the game of nations. It lies instead with those who would passively allow their democratic institutions to be suborned to the benefit of a foreign power Robert Grenier

If there is shame in this saga, it does not necessarily lie with Israel.

Sovereign states have long practised espionage and "covert action", even against "friendly" powers in pursuit of their core national interests. Israel has long done so, and will continue to do so. That question is quite separate from the national policy being promoted, which happens to involve the systematic denial of political rights to an occupied people.

With successive right-wing Israeli governments having essentially precluded the possibility of a two-state solution, the problem for Israel will not go away.

The field of battle has shifted, perhaps conclusively, to the international political arena, where nations will consider whether they are willing to countenance permanent denial of political rights to Arab residents of a unitary "greater Israel". Israel will try to influence those decisions however and whenever it can.

No, if there is shame here, it is not with those playing the "game of nations". It lies instead with those who would passively allow their democratic institutions to be suborned to the benefit of a foreign power.

For the UK, this Al Jazeera investigation is the proverbial wake-up call. The question, for the British and for others, is: Will we sleep on?

Robert Grenier is a retired, 27-year veteran of the CIA's Clandestine Service. He was Director of the CIA's Counter-Terrorism Center from 2004 to 2006. He currently heads ERG Partners, a financial consultancy firm.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.