Weather control, as well as "weather tampering", is expressly forbidden dating from at least December 10, 1976, when the "United Nations General Assembly Resolution 31/72, TIAS 9614 Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques" was adopted.
The Convention was: Signed in Geneva May 18, 1977; Entered into force October 5, 1978; Ratification by U.S. President December 13, 1979; U.S. ratification deposited at New York January 17, 1980.
Expressed need for weather modification
In a November 10, 2005, press release, prior to the U.S. Senate Commerce Committee's November 17, 2005, vote to approve S. 517: Weather Modification Research and Technology Transfer Authorization Act of 2005: A bill to establish a Weather Modification Operations and Research Board, and for other purposes, introduced March 3, 2005, by Senator Kay Bailey Hutchison (R-Texas), Hutchison said "It is critical that we assess and evaluate the efficacy of weather modification research to the extent that lives are saved and property damage is limited ... This work is vital, especially as we near the end of such a devastating hurricane season."
"The bill would create a Weather Modification Subcommittee within the White House Office of Science and Technology Policy and would gather outside experts on a board to advise the subcommittee to expand the scientific understanding of modifying the weather." 
Referring to Hurricane Rita and Hurricane Katrina, as well as "recent tornados and violent storms in the Midwest," Hutchison said that "By developing sustained research we can provide answers to the issues of predictability and reliability of weather modification research." 
When introduced, the bill was read twice and referred to the Committee on Commerce, Science, and Transportation. The bill stated that the act was to take effect October 1, 2005.  Following the Committee's November 17, 2005, vote to approve the bill, it was sent forward to the full Senate for its consideration. 
UN Resolution Key Phrases and Words
One examination of the Convention calls attention to key phrases and words:
- Article I:
- "1. Each State Party to this Convention undertakes not to engage in military or any other hostile use of environmental modification techniques having widespread, long-lasting or severe effects as the means of destruction, damage, or injury to any other State Party."
- "2. Each State Party to this Convention undertakes not to assist, encourage, or induce any State, group of States, or international organization to engage in activities contrary to the provisions of paragraph 1 of this article."
- "This Article of agreement reveals much of the capability of Weather Control techniques. We learn that such Weather Capabilities can produce effects that are:
- a. Widespread -- can cover large geographical areas.
- b. Long-lasting -- Such weather devastation can last for years.
- c. Severe -- "severe damage, destruction, and injury".
- Article II:
- Weather control, referred to here as "environmental modification techniques", means "any technique for changing -- through the deliberate manipulation of natural processes -- the dynamics, composition, or structure of the earth, including its biota, lithosphere, hydrosphere, or of outer space."
- Examples would be:
- Manipulation of a natural process could be altering the flow of the Jet Stream.
- Controlling the dynamics could, again, include the Jet Stream as well as creating rainstorms, thunder and lightening, and hail.
- A change in the "composition or structure of the earth" could refer to earthquakes.
- Damage, injury, or destruction of the "biota" of a nation translates to damage, injury, or destruction of "animal and plant life of a particular region considered as a total ecological entity". In other words, these Weather Control capabilities can wipe out an entire ecological system.
- Damage, injury, or destruction of the "lithosphere" of a nation refers to "the solid outer layer of the earth" which "lies above the semi-fluid asthenosphere [30-150 miles down] and includes the crust and the solid part of the mantle down to about 75 kilometers (47 miles)." This is the area where earthquakes occur.
- Damage, injury, or destruction of the "atmosphere"--including Outer Space--of a nation, or group of nations.
- Prohibiting Military Weather Modification. Hearings before the Subcommittee on Oceans and International Environment, Senate Foreign Relations Committee, July 26-27, 1972.
- Environmental Modification Treaty. Hearing of the Senate Foreign Relations Committee, October 3, 1978. iii, 127 pp. pp. 101-120 are a declassified transcript of a 1974 hearing on military rainmaking in the Vietnam War, with numerous maps defining the areas subject to rainmaking during particular periods.
- DoD News Briefing. Secretary of Defense William S. Cohen, DefenseLINK, April 28, 1997. Secretary of Defense William S. Cohen at an April 1997 counterterrorism conference sponsored by former Senator Sam Nunn.
- Press Release: "Senator Hutchison Holds Hearing on Weather Modification," Office of Kay Bailey Hutchison, November 10, 2005.
- Press Release: "Senator Hutchison's Weather Modification Bill Approved by Commerce Committee. Committee passage clears way for consideration by full Senate," Office of Kay Bailey Hutchison, November 17, 2005.
- "Can We Make Droughts Shorter and Hurricanes Weaker?" Office of Kay Bailey Hutchison, November 18, 2005.
Articles & Commentary
- E. Teller, et al., Weather Control and Ice Ages. Prospects for Physics-Based Modulation of Global Change. August 1997. (pdf).
- Weather/Environmental Tampering with Emphasis on EMP Technology, 1935-1992 Time Line. Begins with Nikola Tesla's 1935 Earthquake Experiments.
- Tom Bearden, Cold War Development of Scalar Interferometry. September 11, 2004. (Word file).
- "Methods of Artificial Weather Manipulation (AWM) help agriculture, devastate the enemy and control the world economy," Indiadaily.com, March 27, 2005.
- Mary-Sue Halliburton, "Weather Modification a Long-Established, Though Secretive, Reality," Pure Energy Systems News, September 6, 2005.
- John Stilgoe, "Learning lessons of weather in war," Boston Globe, November 20, 2005.