-By Steve McClellan

NEW YORK Texas billionaire T. Boone Pickens doesn't take no for an answer.

At least he didn't when NBC -- and sibling cable networks CNBC and MSNBC -- apparently rejected his latest ad stating the case for the U.S. to decrease its dependence on foreign oil.

In the war of words that ensued, Pickens won his fight to get the spot on all three nets.

The ad was rejected Tuesday, according to sources in the Pickens camp, for making unsubstantiated claims and for being "controversial." NBC issued a statement late Wednesday declaring that it never made a final decision on whether to broadcast the commercial.

Clearly, Pickens believed the ad had been barred. On Wednesday, his lawyers sent a letter to NBC and he appeared on Fox News' Neil Cavuto program to express his dismay. A copy of the "lawyer letter" was made public by Pickens at 4 p.m. Wednesday. By 6 p.m., a source close to Pickens said NBC reversed course and accepted the ad for all three networks.

The latest ad is a 15-second spot that says Iran is reengineering domestic cars to run on natural gas so it can sell more oil abroad at hefty rates, while "we're not doing a thing" in the U.S. to cut consumption.

A source said NBC initially rejected the ad on two grounds: controversial subject matter and failure to support the statement that nothing is being done to cut domestic consumption. "The ad is not acceptable for air on the NBC network because the spots address controversial issues and it is our policy not to air ads addressing such issues on our network," NBC wrote in rejecting the ad, said a source who read the letter to Adweek.

In addition, the network said "Iran" was not acceptable for air on the networks "because you have not established to our satisfaction that there is a reasonable basis for the claim that 'we are not doing a thing here.'"

But Pickens and his team were puzzled because all the previous ads they placed, including 60-second spots that the networks did air, were at least equally controversial. For example, in one previous spot, Pickens says when it comes to domestic oil reserves, America should "drill, drill, drill."

The letter sent to NBC on Pickens behalf by the Washington, D.C., law firm Patton Boggs, and dated Aug. 27, charged the network with "selectively applying the First Amendment and denying your viewers access to information that is important to their education and understanding of the issue of energy independence."

Two hours after releasing the letter at 4 p.m. yesterday, NBC approved the Iran ad, without any changes. In a statement issued Wednesday evening, NBC said: "We have been airing seven of the eight advertisements that were submitted for broadcast by T. Boone Pickens. As we were in the process of clearing the eighth, Mr. Pickens released his statement prematurely."

The statement did not address why the network sent Pickens a notice on Tuesday that appeared to reject Iran ad.