Unrealistic...why always only 1 helicopter pursuing

hmmmm...a maniac has control of a nuke in America. The government will only send 1 helicopter at a time after the suspects. The team in the helicopter that was taken down by the emp pursued them for a while yet nobody called in backup...no backup or more gunships? And later, Delroy Lindo's character decides he will "break orders" and pursue people threatening to destroy Denver with only 1 helicopter and the only gunner being Hale, an air force bomber pilot that wouldnt be trained in special forces type combat or riflery. Not to mention Hale has already had quite a long day. The 600,000+ population of Denver is about to be destroyed with a nuke and Delroy's character decides its smart to send only 1 military chopper...we already learned earlier that the nuke can withstand boiling jet fuel for 5 hours so this is ridiculous...why not send in fighter jets or a team of strike helicopters to destroy the train...can you imagine how this would be handled in real life?? WOW