The Sierra Club, with over 700,000 members nationwide, is the oldest grassroots environmental organization in the United States. It sees its purpose as preservation, protection, and enhancement of the natural environment.
Article IV, Section 4. This section is called the Guarantee Clause, because by its terms the federal government makes certain guarantees to the states. One of theseâprotection from foreign invasionâcontinued Congress's prior obligation under the Articles of Confederation.
Article 5 of the North Atlantic treaty, requiring member states to come to the aid of any member state subject to an armed attack, was invoked for the first and only time after the September 11 attacks, after which troops were deployed to Afghanistan under the NATO-led ISAF.