Helaman 4

Mormon teaches why the Nephites seemed to have become weak without the Lord's protection writing - 

"...the Nephites were in great fear, lest they should be overpowered, and trodden down, and slain, and destroyed.

21 Yea, they began to remember the prophecies of Alma, and also the words of Mosiah; and they saw that they had been a stiffnecked people, and that they had set at naught the commandments of God;

22 And that they had altered and trampled under their feet the laws of Mosiah, or that which the Lord commanded him to give unto the people; and they saw that their laws had become corrupted, and that they had become a wicked people, insomuch that they were wicked even like unto the Lamanites."  (Helaman 4:20–22)

The same holds today as the Prophet prayed - 

"Have mercy, O Lord, upon all the nations of the earth; have mercy upon the rulers of our land; may those principles, which were so honorably and nobly defended, namely, the Constitution of our land, by our fathers, be established forever."  (Doctrine and Covenants 109:54)