Britain is sending a hi-tech missile defence system to Poland to protect the NATO nation from Russian warplanes and drones.
A hundred UK troops will be deployed to operate the Sky Sabre weapon, which only came into service with the Army and RAF in December. It was due for Army use two years ago.
It comes after Russia fired 30 cruise missiles into a military base just a few miles from Ukraine's border with Poland.
The deployment was announced by Defence Secretary Ben Wallace on a visit to Poland, which borders war-torn Ukraine and key Russian ally Belarus.
He said: ''We are going to deploy the Sky Sabre medium-range, anti-air missile system to Poland with about 100 personnel to make sure that we stand alongside Poland, protecting her airspace from any further aggression by Russia.”
Boris Johnson ’s spokesman said: “This is a ground-based air defence capability supporting the Polish armed forces at the request of the Polish government.
“It is, as ever, a purely defensive capability which we are providing on a bilateral basis to Poland.
“It will remain under UK control at all times.
“A hundred personnel will be deployed alongside it - they are required to operate the Sky Sabre system.
“It is a short term deployment which will be kept under review.”
The ten-and-a-half foot, surface-to-air missile is operated by 16th Regiment Royal Artillery, based at Baker Barracks, Thorney Island, Hants.
It is designed to provide “360-degree simultaneous coverage and high degrees of manoeuvrability”.
Announcing its arrival into Army service, the Ministry of Defence said: “Sky Sabre marks a massive leap forward in the UK’s armed forces’ capability to defend itself from fast attack jet fighters, missiles and even air dropped bombs.
“Its accuracy and agility means it is capable of intercepting an inbound object the size of a tennis ball travelling at Mach 1.”
The Army said the system could intercept “24 tennis balls all travelling at the speed of sound simultaneously”.
No10 declined to “speculate on what it may or may not be used for”.
But NATO leaders have feared Russian jets and drones attacking Ukraine could stray into Polish airspace - encroaching onto the alliance’s territory.
That would immediately raise the stakes in the escalating conflict, with Russia effectively invading NATO territory.
Such an incursion could trigger NATO’s collective defence clause - Article V - which states that an attack on one member nation is an attack on the whole organisation.
Coalition defence ministers met in Brussels this week to agree to bolster defences on the alliance’s eastern flank following the Kremlin’s invasion of Ukraine.
Asked if it was a response to Russia bombing near the Polish border, the Prime Minster’s spokesman said: “I wouldn’t say it’s in response to one specific issue.
“I think we’ve always seen that both working in NATO and bilaterally with our European counterparts, we want to ensure the borders of Europe are well-protected in light of the aggression we continue to see from Putin.”
