Boris Johnson: West made terrible mistake by failing to punish Vladimir Putin for Crimea invasion

The West made a "terrible mistake" by continuing to rely on Russian oil and gas after the 2014 invasion of Crimea, Boris Johnson has said.

Writing exclusively for The Telegraph, he accused Vladimir Putin of using Russian energy supplies for "blackmail", adding: "We cannot go on like this."

The Prime Minister argued that banning imports of Russian hydrocarbons would "starve" the Russian president of money and "cut him down to size", but admitted a "painful" period of adjustment was to come.

"As long as the West is economically dependent on Putin, he will do all he can to exploit that dependence. And that is why that dependence must – and will – now end," he wrote.

Mr Johnson is expected to visit Saudi Arabia and the United Arab Emirates this week in an attempt to convince Gulf states to release oil reserves to avoid price rises. On Monday, he spoke to the Emir of Qatar by phone about "ensuring sustainable gas supplies''.

There had been calls for him to intervene to secure the help of Mohammed bin Salman, the Kingdom's crown prince, who has strained relations with Joe Biden, the US president.

In his article, Mr Johnson backed new drilling in the North Sea, despite Scottish government criticism, and vowed to make "big new bets" on nuclear power.

He also doubled down on making the UK a "net zero" carbon emitter by 2050, waving away Tory critics by saying the drive towards renewable energy was "not the problem". But there was no mention of the return of fracking – an idea to which Downing Street opened the door last week, but which has split the Cabinet.

On Tuesday, hundreds more Russian businessmen and companies are expected to be hit by UK sanctions as a new law making it easier to take such action takes effect.

However, on Monday night Germany insisted on watered-down EU sanctions against Russia in a move that sparked fury from other members of the bloc.

The Foreign Office is urgently investigating reports that three British former special forces officers were killed in the Russian airstrike on the Yavoriv base near the Polish border on Sunday.

Officials are understood to be liaising with the Ukrainian authorities and international partners to establish further information. Sources told the Daily Mirror that the three were not part of the foreign legion fighting unit being trained there.

On day 19 of the war in Ukraine, Russian artillery struck an apartment building close to Kyiv's centre, killing at least one civilian, injuring more than 10 others and reducing the nine-storey block to a blazing wreck.

Ukrainian officials said the death toll would have been much higher but its air defences had shot down the Russian missile before it hit the ground, sending fragments into the building.

It emerged on Monday that a heavily pregnant woman and her unborn baby died when a Russian bomb hit a maternity hospital in Mariupol last week. A photograph of the woman, clutching her swollen belly and with blood on her thigh as she was carried from the rubble on a stretcher, had shocked the world.

The first humanitarian corridor out of Mariupol was opened up, allowing several hundred civilians to leave the war-torn city after days of "barbaric" and relentless Russian bombardment.

Benjamin Hall, a British journalist working for the US network Fox News, was injured while reporting on the conflict outside Kyiv. He was taken to hospital, but the extent of his injuries was unclear.

At least nine people were killed when a Russian missile struck a television transmission tower and administrative building in Rivne region, about 200 miles west of Kyiv.

In Donetsk, eastern Ukraine, the Kremlin said the Russian-separatist controlled city had been hit by a Ukrainian missile, killing 23 people. Ukraine blamed Russia for the bombing, claiming it was a "false flag" attack intended to justify retaliatory strikes.

In his piece, Mr Johnson criticised the West's response to the Russian annexation of the Crimean peninsula, then part of Ukraine, in 2014 and linked it to last month's invasion.

He wrote: "When Putin invaded Ukraine the first time round, in 2014, the West made a terrible mistake. The Russian leader had committed an act of violent aggression and taken a huge chunk out of a sovereign country – and we let him get away with it.

"We decided we could somehow go back to normality. Economic relations didn't just resume – they intensified, with the West taking more Russian gas than ever before, becoming more dependent on the goodwill of Putin and more exposed to the vagaries of the global gas and oil price.

"And so when he finally came to launch his vicious war in Ukraine, he knew the world would find it very hard to punish him. He knew that he had created an addiction. That is why he feels able to bomb maternity hospitals. That is why he is emboldened enough to launch indiscriminate assaults on fleeing families.

"And as his bombs fall, the cost of oil and gas rises still further, meaning less money in your pocket and more in Putin's. We cannot go on like this.  The world cannot be subject to this continuous blackmail."

The UK has vowed to ban Russian oil imports by the end of this year and is "exploring options" to end Russian gas imports, while the US has blocked both.

But European countries, much more reliant on Russian hydrocarbons, have not gone that far, with the European Commission only announcing a two-thirds drop in Russian gas imports.

Mr Johnson's intervention will be seen as an attempt to convince European countries and allies elsewhere in the world to go further in their import bans.

In an argument speaking to the weakness in the Russian economy, he said Putin was reliant on the money generated by exporting oil and gas.

"Putin's strength – his vast resource of hydrocarbons – is also his weakness", he said. "He has virtually nothing else. Putin's Russia makes little that the rest of the world wants to buy. If the world can end its dependence on Russian oil and gas, we can starve him of cash, destroy his strategy and cut him down to size."

The Prime Minister's official spokesman declined to comment on reports that Mr Johnson is due to travel to the Middle East this week.