European officials are keeping a close eye on the US presidential race and working on a contingency plan, to be implemented if Donald Trump wins the election and subsequently decides to cut off aid for Ukraine.

"When the former and possibly future leader of the free world says that he would sit back and see how Russia would attack NATO allies, we have to rethink what US commitment towards Europe and Ukraine could look like," a European security official said under the condition of anonymity to The Washington Post (WP).

He said: "We should hope for the best but prepare for the worst," adding that the worst-case scenario would see the US dropping support for Ukraine and letting Putin destabilise the region.

The WP reported that European officials have privately discussed building a continent-wide complement to NATO – to work in concert with US security assurances, but also to serve as a "credible alternative" if US guarantees are withdrawn.

However, these conversations are mired in disagreements among Ukraine’s allies.

For example, France and Germany cannot agree on who would foot the bill, while Eastern European countries do not fully trust Western Europe’s resolve against Russian threats. 

"Some are focusing on how to lock in U.S. commitments ahead of the November elections. Senior U.S. policymakers say that, realistically, there is only so much they can do to curb the foreign policy decision-making of future administrations," the WP wrote.

The WP further reported that there is an underlying sense among European officials that "things will change", even if Biden secures reelection.

Bloomberg reported earlier that NATO members are now talking privately about a Russian attack as a danger that requires an immediate response, as they increasingly doubt that the United States will maintain its traditional role of defending Europe as part of the alliance.

In a speech at the Munich Security Conference on 17 February, Ukrainian President Volodymyr Zelenskyy has again urged Western powers to increase military assistance to Ukraine, stressing that keeping Ukraine artificially short of armaments, especially artillery and long-range weapons, "allows Putin to adapt to the current intensity of hostilities".

Also in Munich, Zelenskyy said Kyiv was not considering alternatives to US assistance and that the US remains Ukraine’s key strategic partner.