Polish MiG-29s (Picture: US Department of Defense). — Polish MiG-29s fly alongside US forces – but what do we know about the aircraft? (Picture: US Department of Defense).

Aircraft

What is the MiG-29 and how does it compare to other fighter jets?

Slovakia is considering giving Ukraine 11 MiG-29 fighter jets, according to the country's defense minister.

Slovak Defense Minister Jaroslav Nad said the Soviet-era fighter jets' future could be discussed after they are "most probably" grounded by the end of August, but added no decision had been made yet.

He made the announcement alongside UK Defence Secretary Ben Wallace, who said the UK is not considering giving Ukraine jets, but would help Slovakia guard its airspace.

It comes after MiG-29 jets offered to the US by Poland were rejected as a form of NATO support to Ukraine.

Poland had said it was prepared to hand over the planes to NATO that could then be delivered to Ukraine, but US intelligence has concluded that it could be considered escalatory and trigger a "significant" Russian reaction.

Watch: Russia is constantly looking to upgrade its fighter jet portfolio.

Poland indicated they would want to receive US-made F-16s in compensation.

According to the International Institute for Strategic Studies, Ukraine possessed around 36 of the MiG-29, or Fulcrum, jets before the invasion by Russia.

But what is the MiG-29 and how does it compare to other fighters, like the Russian SU-57, the F-35 Lightning and the F-16?

MiG-29

First operational in 1985, the MiG-29 is a single-seat, twin-engine air-to-air fighter, but would likely be defeated in a dogfight by more sophisticated Russian aircraft, such as the fifth-generation SU-57.

Codenamed Fulcrum by NATO, it is more than 17m long and can hit Mach 2.25, or 2,290 km/h (1,422mph).

As a fourth-generation jet, entering service with the Soviet Union in the early 1980s, it was designed to be able to compete with the US F-16 and F-15 fighters of the same era.

File photo of a US F-16 aircraft (Picture: US Department of Defense).

F-16

The single-seater compact F-16, once a direct competitor to the Fulcrum, is also a multi-role aircraft, used by the US and other nations.

It can hit 1,500mph despite a smaller airframe (14.8m in length) has a fuel capacity of 3,175kg compared to the MiG-29's 3,150kg.

It can locate targets in all weather conditions and detect low-flying aircraft in radar ground clutter.

In an air-to-surface role, the F-16 can fly more than 500 miles (860 kilometres), deliver its weapons with superior accuracy, defend itself against enemy aircraft, and return to its starting point.

Russia's SU-57

The SU-57 is a single-seat, twin-engine multi-role fighter developed by Sukhoi, designed for aerial combat as well as ground and maritime strikes.

At 20.1m long, with a wingspan of 14.1m, the SU-57 is designed to have high endurance and the ability to manoeuvre in all aircraft axes and is Russia's fifth-generation fighter.

The jet can carry four medium-range air-to-air missiles and two short-range infrared homing K-74M2 missiles.

In addition, the aircraft can be equipped with a host of precision-guided bombs, air-to-ground missiles, anti-ship missiles, anti-radiation missiles and cruise missiles.

The SU-57 has a top speed of 2,121km/h (1,317mph). It can fly up to 66,000ft and can climb at a rate of 64,000 feet per minute.

Watch: Royal Air Force F-35s land in Estonia for landmark NATO deployment.

F-35B

The F-35 is billed as the most advanced fighter jet in the world.

The aircraft family includes three variants — all single-seat jets. The F-35A conventional takeoff and landing variant, the F-35B short takeoff/vertical landing variant (STOVL), and the F-35C carrier variant.

The F-35B STOVL variant model was designed to operate from austere, short-field bases and a range of air-capable ships, including the Royal Navy's Queen Elizabeth class aircraft carriers, but can also take off and land conventionally from longer runways at major bases.

The F-35 is used by a number of nations, including the US, Italy, South Korea and the UK. The RAF flies the F-35B and it is the force's most advanced aircraft ever.