For those convinced that Robert Mueller’s investigation into alleged links between the Russian state and the Trump presidential election campaign will ultimately prove a conspiracy, the meeting between Donald Trump Jr and a lawyer with links to the Kremlin, Natalia Veselnitskaya, has long been positioned as a kind of smoking gun.

Back in June 2016, Trump Jr – along with Jared Kushner and Paul Manafort, who at the time was managing Trump Senior’s campaign – hosted a group including Veselnitskaya at Trump Tower, after it was suggested that information could be provided about Hillary Clinton. Since campaign finance rules prohibit the receipt of assistance from foreign governments or nationals, the gathering had (and still has) the potential to get Trump Jr into hot water.

From the moment last summer that the New York Times revealed the meeting had taken place, the Trump camp has maintained that – in the event – no material information about Clinton was discussed. Instead, they contended, Veselnitskaya simply wished to discuss concerns about the Magnitsky Act (used by the US to punish Russian officials suspected of human rights abuses) and in particular an associated adoption programme.

Nonetheless, Trump opponents have long argued that the outcome of the meeting is irrelevant. When Donald Jr was offered dirt on his father’s rival for the presidency by a group of Russian nationals he should – say critics – have told the FBI, not got his diary out.

The latest twist is that the president has finally admitted himself that the reason the meeting took place was “to get information on an opponent”, adding that it was “totally legal and done all the time in politics”. While Donald Jr has previously acknowledged – after an initial denial – that he went into the meeting expecting to receive material that would prove detrimental to Clinton, his dad’s admission is the first occasion we have heard it from the White House. Given that Trump Snr dictated his son’s original disavowal of the claim, it seems significant.

It also follows hot on the heels of Trump tweeting that the Mueller inquiry (aka “this Rigged Witch Hunt”) should be stopped “right now before it continues to stain our country any further”. This, said the president’s press secretary, was not a presidential order to the attorney general Jess Sessions, mind you, but simply Trump’s “opinion”.

On the one hand, then, we have what appears to be an effective admission by both the president and his son that the meeting was set up because it was believed a Russian national with known links to the Kremlin had some juicy goss on Hillary Clinton. And on the other, we have the inquiry established to investigate alleged links between the Trump campaign and the Russian state constantly attacked by those it is investigating. It is, to say the least, a bizarre situation.

But of course, Donald Trump is a bizarre president. He is as likely to believe that Mueller and his team will not – in the final analysis – find enough to tie him into a conspiracy, as he is to think that he will be able to find a way to shut the inquiry down just as it’s about to deal him a fatal blow. If his mind is as confused as his Twitter feed suggests, it is almost impossible to work out what he is thinking.

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However, what is certain is that Trump has managed consistently to keep the public’s attention – and considerable political pressure – on the inquiry. True, just as his criticisms of Mueller’s work infuriate his opponents, they are accepted at face value by his supporters: so few minds are likely to be changed. Nonetheless, would it not be sensible to consider whether the constant barrage of tweets on the inquiry are – whether deliberately or not – providing a distraction from Trump’s day-to-day approach to domestic and foreign policy?

The president’s favoured narrative is that the media and his opponents regularly fail to give him his dues when things are going right, concentrating instead on the “fake news” of Russian collusion. This allows him to assert his many supposed achievements, while maintaining the world’s focus on issues that are contentious but which may never be resolved (or at least not so clearly as to bring Trump down).

So what of these achievements? There is widespread agreement that the US economy is in better shape now than it was two years ago – although where the credit for that lies is the subject of heated debate. What’s more, Trump’s much heralded “trade war” has hardly paid off in the spectacular way he promised. Meanwhile, his programme of tax cuts (arguably the main legislative achievement of Trump’s presidency) have not produced the kind of swift boost to business investment that Republicans said it would – while at the same time increasing the budget deficit.

When it comes to immigration, Trump has managed to secure legal backing for his travel ban from several Muslim-majority countries: but since the premise for that ban was largely rhetorical, its practical impact for Americans has been minimal. Meanwhile, at the Mexican border – where there is no sign of Trump’s promised wall – the administration responded to rising levels of illegal immigration by locking children in cages, denting America’s global image while having seemingly little impact on potential future migrants’ intentions.

In his foreign policy approach, too, big talk has not led – quite – to big achievements. Trump’s direct involvement in negotiating with North Korea may indeed have reduced tension on the Korean peninsula, but it remains to be seen whether it was a case of Trump being a global player, or simply being played by his rocket man pal, Kim Jong-un.

Robert Mueller’s inquiry must, whatever the president says, be permitted to reach a proper conclusion. If a conspiracy to affect the course of the last election is eventually proved there must, indeed, be a reckoning.