Erika Kirk, the widow of conservative activist Charlie Kirk, described him as a "perfect" husband and father, and said the "evildoers" who assassinated him have no idea what they have unleashed.
NATO is to bolster Europe's eastern flank, including the use of UK military resources, after Russia's "reckless and unacceptable" violation of Polish airspace.
Thousands of troops are taking part in a joint military exercise between Russia and Belarus, as tensions with the EU run high following a Russian drone incursion into Polish airspace earlier this week.