I don't doubt for a minute that somewhere in the future of America, a war and battle will rage on our soil like never before. How soon, is anyone's guess, but only God knows. All we as Christians really can do is to establish our relationship with the Lord, keep our eyes on Him, and learn to know and obey His voice. Whatever happens in the future, is in the hand of the Lord, and we are safe in Him. Whether we live, or whether we die, as disciples of the Lord Jesus, we should not speak with fear of these things, because Jesus commanded us not to fear these things. Our hope is in eternity, and not in this world. Why America has been spared persecution for so long, I do not know. And there is no way to know how much longer America will be spared, but... one thing is for sure... Paul writes very clearly:
II Tim. 3:12 Yea, and all that will live godly in Christ Jesus SHALL suffer persecution.