The American deal will be the 15th of more than 30 bilateral agreements signed between Kyiv and its Western allies since the idea was conceived on the fringes of a Nato summit in Vilnius, Lithuania last July.

Like its allies, Washington’s offer will not contain a specific monetary pledge or a promise of a mutual defence clause, similar to Nato’s Article 5.

Instead, Ukraine will be able to trigger emergency consultations over future weapons shipments, troop training programmes and the reintroduction of Western sanctions if Russia mounts another attack on the country.

The UK, France and Germany included similar provisions in their security agreements with Kyiv.

It has taken months of negotiations to broker the pact between Washington and Kyiv because the Biden administration decided to focus on unlocking a $60 billion aid package that was stalled by pro-Trump Republicans in Congress.

The Ukrainians will welcome the deal, but Volodymyr Zelensky, Ukraine’s president, has previously warned such agreements are no substitute for Nato membership.

Nato sources have told The Telegraph that the dozens of memoranda of understanding will be brought together under an umbrella agreement backed by the alliance to further reassure Kyiv of the West’s commitment to maintain support for the war effort.

“Hopefully the US will agree and then I think we will see some sort of presentation of these bilateral memoranda of understanding with a chapeau on it. But basically we’re waiting from the Americans, they’ll come up with a proposal,” a senior alliance official said.

It has been suggested that Nato could officialise its support for the security deals in the summit communique agreed by leaders in Washington to demonstrate to Kyiv that there is a “well-lit bridge” to membership.