LONDON • Frustrated for decades, they finally lost their patience: In a move which surprised President Barack Obama's officials, US lawmakers decided to forbid the use of US taxpayers' money to subsidise the sale of eight F-16 fighter jets to Pakistan.

This was one of those rare occasions when the US executive branch lost a weapons deal on Capitol Hill, and especially a defence contract aimed at bolstering one of the United States' closest allies. But that was precisely the problem, for Pakistan is no longer considered an ally by both Democrats and Republicans in Congress, angered by what they see as Pakistan's policy of supporting terrorist networks in neighbouring Afghanistan, as well as Pakistan's alleged connivance in exporting violence to India.

The episode was hailed by congressmen as the beginning of a new US policy of punishing allies which not only fail to provide an adequate return for the heavy US investment in their nations and militaries, but actually act as an obstacle to US security interests. And the mood of impatience with allies which fail to "deliver" - as Washington's fashionable parlance now puts it - is intensifying from all quarters: President Obama criticises European "free riders" who demand US security guarantees without offering a payback, while Republican presidential candidate Donald Trump dismisses most of the US military alliances as simply a waste of money.

Still, Washington's current frustration with its closest allied nations is hardly remarkable. For all big powers invariably end up paying more for their alliances than they ever get back. And allies frequently succeed in controlling their patrons rather than being controlled by them; this is a classic example of the tail wagging the dog.

PAKISTAN A STRIKING EXAMPLE

As US lawmakers see it, Pakistan is perhaps the most striking example of an ungrateful ally. The US has poured tens of billions of dollars into the Pakistani military for over half a century. But that has only allowed Pakistan to divert resources towards the production of nuclear weapons, as well as subsequently engaging in the sale of nuclear technology to other nations, most of which are US enemies. Pakistan has also harboured militant groups that were responsible for at least a chunk of the 2,300 US soldiers killed in Afghanistan since the Sept 11 terrorist attacks of 2001.

To add insult to injury, Pakistani politicians brazenly deny all these accusations, notwithstanding the fact that the intelligence services of all major global powers have plenty of evidence that they are true. And Pakistan's immediate reaction after the US discovered that it sheltered Osama bin Laden was not to apologise; instead, the Pakistanis arrested Shakil Afridi, the doctor who cooperated with US intelligence in capturing the Al-Qaeda leader.

US officials have argued that their engagement with Pakistan is a way of helping it become a prosperous, stable country with an open, pluralist political system. But as Mr Lawrence Wright, a prize-winning US investigative journalist who has written extensively about Pakistan, once told US officials: "India has become the state we tried to create in Pakistan."

In short, Pakistan may now be a complete liability.

Nor is Pakistan's defiance unique among the US allies. The smaller Gulf monarchies would not exist without the US security umbrella, but US officials often find it difficult to tell their Gulf partners that they should not pursue policies which are contrary not only to US security interests, but also to those of other Western allies in the region.

And then there is Israel, the country which prides itself on being the US' closest Middle Eastern ally, yet is often nothing of the sort. As Mr Dov Zakheim, an Orthodox Jew and ardent supporter of Israel who served as Undersecretary at the US Department of Defence in 2003 subsequently recalled in his memoirs, he was "definitely not amused" when, on the eve of the US-led invasion of Iraq, Israel offered the Americans military support, while insisting that the Americans would "of course" have to pay for any Israeli assistance.

More recently, Israeli Prime Minister Benjamin Netanyahu not only ignored President Obama but actually made a virtue of it; Mr Netanyahu appears to have triumphed in this confrontation, for he seems set to remain in office long after Mr Obama vacates the White House.

WEARY OF FOREIGN ADVENTURES

With the US public tired of foreign policy adventures and its political elite eager to husband the country's resources, it is no wonder that the question of how to ensure that US allies contribute more to the US security is now coming to the fore.

In his usual crass way, Mr Trump has elevated the matter to one of his guiding foreign policy plans. Although Democratic presidential candidate Hillary Clinton has been silent on this matter, there is no question that, as the electoral campaign gains traction, she will be forced to pledge to get tougher on US allies.

And there is no shortage of foreign policy specialists eager to offer ways in which the US can force its allies to do more of Washington's bidding, or suffer the consequences.

In an analysis published recently, Mr Jeremy Shapiro of the European Council on Foreign Relations and Mr Richard Sokolsky of the Carnegie Endowment for International Peace, a distinguished US academic establishment, argued that the US way of handling its alliances owes much to the Cold War age when the mere act of collecting allies was in itself a policy. That, argue the two experts, now has to change; the US, they write, "should focus less on making our allies happy and more on making them actually behave like allies".

But although few can quarrel with the logic of this argument, it may also be taking matters too far. First, it is worth noting that the US is hardly the only country to discover that it cannot translate money into influence, and it cannot make its allies do precisely what their patron may want. The former communist regimes of Eastern Europe were utterly dependent on the Soviet Union for their survival, but the USSR was never able to make them do exactly what Moscow wanted.

The Chinese poured huge investments into Myanmar but found themselves suddenly dumped. And although China has huge influence in Cambodia, the Chinese are only too aware of the saying that one never actually owns Cambodia; one merely rents it for a period. In short, the frustration which Washington feels about its allies' performance has been and is being shared by other powers.

Furthermore, criticising allies for not doing enough to meet the needs of their protectors tends to ignore the contributions which allies do make, and often at considerable costs to themselves.

Japan, for instance, had absolutely no interest in imposing economic sanctions on Russia in the aftermath of the Russian military involvement in Ukraine, but did so in order to show solidarity with the US.

And Romania, to use an example from Europe, has no interest in what is going on in Afghanistan, but it has sent troops there and has just lost two of its soldiers in a battle in that faraway country precisely because it wanted to prove that it is willing to fulfil its responsibilities as a US ally.

But when US politicians criticise their allies, they are not even aware of how many efforts those allies actually make to serve US strategic objectives; the US gets back from its alliances quite a number of advantages Washington officials are not even aware of.

And finally, browbeating allies into contributing more is not the best or the most diplomatic approach. Instead, what Americans need to do is to articulate their needs more directly to each ally, as well as engage in a more honest debate with Congress in Washington about what are the key objectives which the US is seeking from each one of its current allies.

It may be that some allies, like Pakistan, will ultimately have to be cut loose by Washington. But US leaders owe it to their people to resist the growing temptation to lash out against seemingly ungrateful allies.

For many of the US' closest friends contribute quite a bit, and are willing to do even more, if properly asked by the next occupant of the White House.