The head of MI6 has claimed Russia's attack on Ukraine was a "long planned, unprovoked" strategy carried out with "cruel aggression".
Richard Moore tweeted that the invasion have been brewing for many months.
Moore, known in Whitehall as C, says there is no disguising the intent - and says Vladimir Putin carefully orchestrated the attacks, which got underway on Thursday morning.
The MI6 boss tweeted that "US and UK intelligence communities uncovered Putin's plans for Ukraine ".
He said: "We exposed his attempts to engineer 'false flag', fake attacks to justify his invasion. We revealed his plans to assassinate Ukrainian leaders and senior officials.
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"This attack was long planned, unprovoked, cruel aggression.
"No amount of Russian disinformation will now disguise that fact from the international community."
It comes as The Duke of Cambridge made a secret visit to MI6 - just hours before Russia launched its deadly attack on Ukraine.
Prince William visited the Secret Intelligence Service, which deals with foreign intelligence and protects the UK from risks abroad, in London on Wednesday morning.
In 2019, William spent three weeks working with MI5, MI6 and GCHQ to learn about how the UK's security and intelligence agencies worked.
His visit came as the Russian President said allies of Ukraine who try to interfere with his attack will "face consequences greater than any you have faced in history", in a chilling warning.
The invasion began after a pre-dawn TV address, in which Putin demanded Ukraine's military lay down its arms.
Ukrainian officials say 57 of their citizens have been killed and 169 wounded in the attacks.
Some 100,000 people have left so far, the UN confirmed.
Meanwhile, more than 1,700 people have been arrested during anti-war protests across dozens of cities in Russia, according to reports.
Around 900 were arrested in Moscow and over 400 in Saint Petersburg.
Ukrainian protesters hit the streets of London today as they pleaded with the UK to do more to stop Putin taking over their country.
Hours after the attacks begun, hundreds of demonstrators gathered outside Downing Street to call for more drastic action from Britain and its Prime Minister, wanting a "total isolation of Russia ".
The UK today retaliated as they moved to cripple Russian banks’ access to the UK's financial institutions and curtail oligarchs luxury lifestyles in the capital.
They were announced as part of measures Prime Minister Boris Johnson said were designed to stunt Russia's economy.
