A formidable cold front is set to grip the nation, with meteorologists warning of a dramatic temperature drop that could leave even the sunniest states shivering.

Experts, former officials, some lawmakers and international observers have questioned the legality of the strikes.

A fierce cold snap is in the forecast for the central and eastern U.S. early next week, forecasters warned, with record-breaking cold possible.

This week is delivering the hottest temperatures of the year so far to much of the eastern United States. See detailed maps about the latest heat index forecasts. Note: Forecast data is as of 7:17 a.m ...