In sanctioning five Russian banks and three oligarchs, Mr Johnson accused Russian President Vladimir Putin of “establishing the pretext for a full-scale offensive” against Ukraine and said “further powerful sanctions” would follow if that happened.
“This the first tranche, the first barrage of what we are prepared to do and we hold further sanctions at readiness to be deployed,” Johnson told British lawmakers.
Mr Johnson said Russian tanks and armoured personnel carriers have been spotted in the separatist Ukrainian regions recognised as independent by Russian President Vladimir Putin.
He said that amounts to “a renewed invasion” of Ukraine.
Mr Johnson said nations including the UK, France, Germany and the US had “tried to find a peaceful way through this crisis,” but “by denying Ukraine’s legitimacy as a state … Putin is establishing the pretext for a full-scale offensive.”
“We must now brace ourselves for the next possible stages of Putin’s plan: the violent subversion of areas of eastern Ukraine by Russian operatives and their hirelings, followed by a general offensive by the nearly 200,000 Russian troops gathered on the frontiers, at peak readiness to attack,” he told the UK Parliament.
“If the worst happens, then a European nation of 44 million men, women and children would become the target of a full-scale war of aggression, waged without a shred of justification, for the absurd and even mystical reasons that Putin described last night.”
Mr Johnson told lawmakers sanctions would hit Rossiya Bank, IS Bank, General Bank, Promsvyazbank and the Black Sea Bank.
He said three Russian oligarchs with interests in energy and infrastructure — Gennady Timchenko, Boris Rotenberg and Igor Rotenberg — will have their assets frozen and be banned from travelling to the UK.
All three have already been sanctioned by the United States.
The UK Prime Minister said he was willing to send more troops to join NATO’s battlegroup in Estonia.
He said, “Putin’s venture in Ukraine must fail, must ultimately fail and be seen to fail,” he said.
“That will require the perseverance, the unity and the resolve of the entire Western alliance, and Britain will do everything possible to ensure that that unity is maintained.”
The European Union also put some of its cards on the table saying its sanctions would centre on several Russian officials, banks financing the Russian armed forces and include a move to limit Moscow’s access to EU capital and financial markets.
The West insisted Mr Putin’s bold moves in Ukraine violated countless international agreements and since the words of diplomacy had failed, it was time to move towards action.
With Western powers long having made clear that the fate of Ukraine wasn’t worth a hot and direct military confrontation with Russia, and the potential of a world war, sanctions were the only, limited, option to crystallise their anger.
“Now it’s up to the international community to react to this one-sided, incomprehensible and unjustified action by the Russian president,” he told reporters in Berlin, adding that it was necessary to “send a clear signal to Moscow that such actions won’t remain without consequences.”
Washington has for years argued that building another pipeline bringing natural gas from Russia to Germany increases Europe’s reliance on Russian energy supplies.
“No lows too low, no lies too blatant, no red lines too red to cross,” Lithuanian Prime Minister Ingrida Simonyte said in summing up the political disgust felt from Europe to North America and democracies hugging Russia’s borders in Asia like Japan and South Korea.
However, Putin continued to knock the world off-kilter with a strategy where confusion about the true extent of an invasion, which would automatically kick in major sanctions, remained unclear and debatable.
Russia says it’s sending what it deems “peacekeepers” into eastern Ukraine, but EU foreign policy chief Josep Borrell stressed they were “troops” on sovereign Ukrainian territory.
“I wouldn’t say that’s a fully fledged invasion, but Russian troops are on Ukrainian soil,” he said.
The latest developments were enough to force the 27-nation bloc into a mode of high alert, and the EU’s foreign ministers would be deciding later on Tuesday (Wednesday AEDT) on how deep a first batch of sanctions, including those put forward early on Tuesday by European Commission President Ursula von der Leyen and European Council chief Charles Michel, would have to cut.
It would likely stop far short of the “massive” package threatened by the EU and Washington for a full military invasion into national territory that Kyiv still controls.
“The way we respond will define us for the generations to come,” Ms Simonyte said.
Too much too soon, though, could also hurt the international response, Austrian Chancellor Karl Nehammer said.
“There is a variety of sanctions options that now need to be used in a targeted way, because we have to assume that we haven’t yet reached the peak of the escalation,” he said.
A conflict could devastate Ukraine and cause huge economic damage across Europe, which is heavily dependent on Russian energy. But Asian nations are also worried.
President Moon Jae-in instructed his officials to prepare for the economic fallout in South Korea if the Ukraine crisis worsens and US-backed nations levy stringent economic sanctions on Russia.
Hopes are dwindling that a major conflict can be averted.
He blamed NATO for the current crisis and called the US-led alliance an existential threat to Russia.
The global condemnation came amid rising skirmishes in the eastern regions of Ukraine that Western powers believe Russia could use as a pretext for an attack on the Europe-facing democracy that has defied Moscow’s attempts to pull it back into its orbit.
New Zealand Foreign Minister Nanaia Mahuta said there was no basis under international law for Putin to recognise the Ukrainian separatist regions.
“We are concerned that this is a calculated act by President Putin to create a pretext for invasion, which would be a clear act of aggression. We again call for urgent diplomatic efforts to find a peaceful resolution,” Ms Mahuta said in a statement.
Those on a saddle between Russia and the West were in an uncomfortable position.
NATO-member Turkey, which has close relations to both Ukraine and Russia, criticised Moscow’s decision to recognise the independence of the regions in eastern Ukraine.
“We consider this decision by Russia as being unacceptable,” Turkish President Recep Tayyip Erdogan said.
“We reiterate our calls to the parties to respect common sense and international law.”
China, a traditional ally of Russia, sounded a cautious note, calling for restraint and a diplomatic solution to the crisis.
Washington could be much more straightforward.
The White House issued an executive order to restrict investment and trade in the separatist regions, and additional measures — likely sanctions — were to be announced on Tuesday.
Those sanctions are independent of what Washington has prepared in the event of a Russian invasion, according to a senior administration official who briefed reporters on the condition of anonymity.
With an estimated 150,000 Russian troops massed on three sides of Ukraine, the US has warned that Moscow has already decided to invade.
Still, President Joe Biden and Mr Putin tentatively agreed to a meeting brokered by French President Emmanuel Macron in a last-ditch effort to avoid war.