The US has authorised sending F-16 fighter jets to Ukraine to reinforce the nation's air defence within the wake of a barrage of Russian missiles.

But what number of might be delivered, and which nations will present them?

US President Joe Biden authorised Western allies to provide superior F-16 fighter jets - a transfer the UK, Netherlands, Belgium and Denmark have welcomed.

On Friday, Prime Minister Rishi Sunak tweeted: "The UK will work together with the USA and the Netherlands, Belgium and Denmark to get Ukraine the combat air capability it needs. We stand united."

Here’ Sky News takes a better have a look at the F-16 fighter jets and their significance.

Why would F-16s be so necessary for the battle?

Sky News' army analyst Sean Bell says that though Russia has extra tanks and plane, the folks of Ukraine are proving tenacious and brave on the battlefield.

Ukraine has gained confidence with the West offering extra help and longer-range weapons. However, in the meanwhile, Mr Bell mentioned Zelenskyy has been asking for the aptitude for the previous yr, including "fighter aircraft are the one thing that he can't match Russia with."

He provides that if the west gives manned fight plane, then the Russian air pressure "most certainly wouldn't stand a chance."

The F-16s maintain significance in supporting Ukrainians within the battle, however Mr Bell says it'd take months and even years for army troops to discover ways to function the plane.

He mentioned: "So this is not something unlike most of the narratives in the west, by just giving equipment.

"This is about giving functionality. And Zelenskyy has been banging the drum up till now.

"The west has been reluctant to do that because they know it will take time, but it would prove a very decisive capability in this conflict."

What are the F-16s?

The F-16 is constructed by the American defence contractor Lockheed Martin.

It is a multi-role fighter plane created for the United States Air Force.

The F-16 has an inner M61 Vulcan cannon and 11 places for mounting weapons and different tools.

Its payload sometimes consists of two 2,000lb (907kg) bombs, two AIM-9 Sidewinder short-range air-to-air missiles, two AIM-120 medium-range air-to-air missiles and two 2,400lb (1088kg) exterior gas tanks.

The jet can journey at speeds as much as 1,500mph and has a spread of greater than 2,002 miles.

It has a wingspan of 32ft 8in (9.9m) and a size of 49ft 5in (13.8m). It weighs 19,700lb (8935kg) with out gas and has a most takeoff weight of 37,500lb (17010kg).

There is each a single-seat and two-seat mannequin of the plane.

In 1991, in the course of the Gulf War, F-16s have been used to assault airfields, army manufacturing services and different targets.

It has additionally been used and flown in American conflicts in Afghanistan, Iraq, Kosovo and the Persian Gulf.

They are operated by a number of nations apart from the US, together with Poland, Belgium, the Netherlands, and Denmark.

When can F-16s be realistically delivered?

There are two key components to consider.

As F-16s are produced by the US, the Americans would wish to supply permission to different nations to provide their F-16 plane.

"The second thing is F-16s are the most widely exported aircraft in the world as there are a lot of them about," Bell provides.

There are two components to contemplate for the F-16s plan to fall into place.

First, coaching should happen to make sure pilots can fly the plane.

And second, it is necessary to consider how the F-16s will truly be delivered.

Bell added: "Although there's lots of countries operating them because it's so expensive, nobody has more aircraft than they need, and nobody could afford to give to 20 to 30 of these platforms to Ukraine."

Which nations may present F-16s?

At the second, there are round 25 nations that at the moment function the F-16.

The fighter jets come at a excessive value, and Bell says that though many nations have them, "none of them have spare aircraft."

He provides: "They're just too expensive. You generally buy what you can afford and that's not enough for everything you want to have them for.

"So not one of the nations will be capable of do away with extra jets. But I think what's going to occur is that they might want to give attention to a commonality of jets.

"So who operates a certain block and a certain age of aircraft and see whether there is some shuffling behind the scenes that different countries can give each other aircraft so that you get a common aircraft that comes to Ukraine."

Read extra from Sky News:Zelenskyy meets Sunak at G7 in Japan as US approves sending F-16 fighter jets to UkraineAnalysis: Vladimir Putin's 'undefeatable' missile was a costly illusion

How quickly may Ukraine begin utilizing it?

US officers have estimated that it may take 18 months for coaching and supply of the jets.

On Monday, Emmanuel Macron mentioned France was open to coaching Ukrainian pilots immediately.

London has agreed to begin coaching pilots within the spring and mentioned it might have a look at shortening the periods for skilled Ukrainian pilots.

UK Defence Secretary Ben Wallace mentioned on Wednesday: “This just isn't about gifting weapon programs.

"This is about gifting a platform. If anyone follows Formula One, you don’t just gift a car, you have to gift a pit team."