France and the UK will support Ukraine in its fight against the Russian invasion "for as long as it takes", and it is important that President Vladimir Putin is defeated.

"Britain and France have been staunch supporters of Ukraine and we will continue to be for as long as it takes... I have no doubt that we can make sure Putin loses and it is essential he does lose," AFP cites UK Foreign Secretary David Cameron after talks in Paris with his French counterpart Catherine Colonna.

"We must be absolutely staunch in how we back Ukraine," he added.

Insisting that the West must stay the course, Cameron likened the fight against the Russian invasion to a play made up of different acts.

Cameron noted that "the first act was the stunning failure of Russia to achieve its objectives" at the initial stage of the invasion.

"The second act was the brilliance the Ukrainians showed in driving back the Russians... and of course the third act has been more difficult on land," he pointed out, referring to the Ukrainian counteroffensive operations this summer, when a breakthrough failed.

Cameron stated that the fourth act has not been written yet and "we must be sure we write it in the correct way".

Both Cameron and Colonna were keen to emphasise that the UK and France remain on the same page on major international issues, including Ukraine and the Middle East, even after Brexit.

On Monday 18 December, the White House warned that current funds will only be enough for one military aid package to Ukraine before the end of the year.

Pentagon Comptroller Michael McCord alerted the heads of pertinent US Congress committees that the agency only has enough funds to continue supplying military aid to Ukraine until 30 December.

The US Senate and therefore Congress in general are unlikely to advance new border security restrictions, on which the allocation of billions of dollars in aid to Ukraine depends, by the end of the year.