With European leaders reeling from the US - their once most reliable ally - siding with Russia in the United Nations, calling Ukraine's President Volodymyr Zelenskyy a "dictator without elections" and suggesting Kyiv is to blame for the war, Sir Keir made his move - stepping up on Britain's commitment to defence, to NATO and both its European and US allies.
The prime minister, announcing his decisions to redirect some of the UK's foreign development and aid budget into defence to pour an additional £13.4bn a year into defence spending by 2027, said it was the biggest increase in defence spending since the Cold War.
This decision is an acknowledgement from the British government that the peace dividend the UK and Europe took after the fall of the Berlin War is long gone, that the nation must now reinvest in its defence and security, rebuild its defence industry and put that above other priorities.
But what this commitment does give Sir Keir is something to offer President Trump when he goes to the White House on Thursday, asking the US to provide security guarantees to Ukraine as part of any peace deal.
Washington demanded that those in the security alliance step up military spending, calling for 5% of GDP to be spent on defence - more than double the alliance's current spending target.
