They needed to send a helicopter....to an Air Force base.
Yep, they needed the host country to send a helicopter to a US base overseas.
Quality journalism. *sigh*
RAF Mildenhall belongs to the British Ministry of Defence. Security is provided by the MOD on the civilian side of the base.
The USAF uses the base mainly for military air transport and refueling aircraft and at one time, the SR-71. The flightline, (business side), security is USAF security personnel.
If a car were to run the front gate, the MOD has the responsibility of responding to the situation. USAF SF could assist, but it is only for containment. It is against international agreement for a US service member to harm a citizen of the UK. If the car tried to enter the business side, all bets are off.
On a side note, RAF Mildenhall use to host the Paris Air Show every other year. I stayed at the Bird in Hand hotel, which is right outside the gate, when I first arrived in the UK.