British Foreign Secretary David Cameron gave the hard sell on continued United States support for Ukraine as he toured Washington on Thursday.

Speaking at the Aspen Security Forum, Cameron acknowledged that politicians on both sides of the Atlantic are asking why they should focus on “challenges overseas” amid turmoil at home.

But, speaking after Republicans in the U.S. Senate blocked fresh funding for Ukraine, the former British prime minister said Vladimir Putin’s invasion of the country marked “the worst example of one state invading and wrecking the sovereignty of another state that we’ve seen since the Second World War.”

And he urged Americans to “recognize that European security is also American security” — or risk handing a gift to Russia and China.

“We should pass this money to the Ukrainians, we should back them and make sure that it’s Putin that loses — because if that money doesn’t get voted through, there are only two people that will be smiling: One of them is Vladimir Putin in Russia,” Cameron said.

“The other one is Xi Jinping in Beijing. And I don’t know about you, but I wouldn’t want to give either of those people a Christmas present.”

Cameron was a surprise reappointment to the British government last month as his successor Rishi Sunak tried to shake up a government struggling in the polls. 

He is just the latest senior British figure to be dispatched to D.C. to shore up support for Ukraine, with former Prime Ministers Liz Truss and Boris Johnson also making trips in recent months aimed at bolstering Republican backing.