Boris Johnson believes it will put additional economic pressure on Vladimir Putin
New sanctions - including against Russian banks and oil tycoons - are being imposed by the UK.
The British Prime Minister says the sanctions will tighten the "economic vice on Putin".
The invasion of Ukraine is being discussed at three key meetings today - NATO's meeting is currently under way.
Meanwhile in Ukraine, an agreement has been reached on seven humanitarian corridors to evacuate civilians from towns and cities.
Following a meeting with the President of the Red Cross, Russian Foreign Minister Sergei Lavrov described what he believes is taking place on the ground:
