Where is RAF Mildenhall, why was the Suffolk site on lockdown and what is the US air base used for?
A US airbase in Suffolk was put on lockdown after a car rammed into its gates.
But what is RAF Mildenhall normally used for, and what was the security incident?
Where is RAF Mildenhall?
Royal Air Force Mildenhall is a RAF station located near Mildenhall in Suffolk.
What is the air base used for?
Despite its status as a Royal Air Force station, it primarily supports United States Air Force (USAF) operations, and is currently the home of the 100th Air Refueling Wing (100 ARW).
On 8 January 2015, the United States Department of Defense announced that operations at RAF Mildenhall would end (along with those at RAF Molesworth and RAF Alconbury), and be relocated to Germany (Spangdahlem Air Base) and also elsewhere within the UK.
On 18 January 2016, the British Ministry of Defence announced that the site would be sold.
What's its background?
RAF Mildenhall has the largest US Air Force (USAF) presence in the UK, along with RAF Lakenheath.
The site was first built for the Royal Air Force in 1933 and taken over by the US military in 1950.
The decision followed the 1950 invasion of South Korea by Communist forces, when it was decided to re-establish a strong American force in Europe.
Following the announcement that the site will be sold, it has been reported that the USAF will stay at the site until 2024.
The air base has had a few high-profile visitors too. King George V reviewed 350 aircraft there in 1935 on the occasion of his Silver Jubilee.
And five years ago RAF Mildenhall welcomed the then US First Lady Michelle Obama who met American military families based there.
Has Mildenhall been targeted before?
Both Mildenhall and Lakenheath have been targeted by protesters in the past.
About peace campaigners from the Campaign for Nuclear Disarmament demanded the removal of around 100 nuclear bombs at Lakenheath in 2006.
In the same year, activists camped outside Mildenhall in protest at US flights refuelling there on the way to Isreal, reported the BBC.
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Why did police put it on lockdown?
The airbase was put on lockdown after a car tried ramming the gates.
RAF Mildenhall was on high alert over the "significant security incident" on the afternoon of December 18, the Ministry of Defence has confirmed.
US military personnel opened fire on a driver as he tried ramming his way through.
A Suffolk Police spokesman said: "Suffolk Police were contacted at approximately 1.40pm today ( Monday 18 December) to reports of a disturbance at RAF Mildenhall in Suffolk.
"The base was put into lockdown and units responded immediately.
"Shots were fired by American service personnel and a man has been detained with cuts and bruises and taken into custody.
"No other people have been injured as a result of the incident."
Last year, an ISIS supporter was caged for life after planning a terror attack on five US Air Force bases in the UK - including RAF Mildenhall.
Delivery driver Junead Khan, 25, from Luton, used his job with a pharmaceutical company as cover to scout the bases.