Trump said he told NATO allies that if they’re not going to pay their bills, he won’t defend them.

Kristen Welker hosts NBC Pentagon correspondent Courtney Kube, Jonathan Martin of Politico, Symone Sanders Townsend, former spokeswoman for Kamala Harris, and Marc Short, former director of legislative affairs for President Trump,

Europe is staring down the barrel of a stark new reality where the United States being the backbone of NATO – the alliance that has guaranteed the continent’s security since 1949 for almost 80 years – is no longer a given.

Italian Prime Minister Giorgia Meloni has suggested NATO's Article 5 protection could be extended to cover Ukraine even if it is not a full member state, suggesting this would be better than options such as the deployment of peacekeeping forces to monitor a ceasefire.

The president has discussed possibly favoring members of the alliance that spend a set percentage of their GDP on defense, sources told NBC News.

Uneasiness grows over continued U.S. support for the 75-year-old alliance as Trump casts doubt on support from other members if attacked.

NATO Secretary General Mark Rutte said that increased defense budgets by European governments were the first step in securing the continent and that contractors need to play their part by increasing output.

Ukrainian president Volodymyr Zelensky labelled it as "genocide". Former US Army Europe commander Ben Hodges warned that a war against NATO could see Russia targeting crucial transport infrastructure, implying "airports and seaports" could be under threat.