President Bush had words with Russian President Vladimir Putin Monday about the sale of sensitive military equipment to Iraq, but the discussion may be moot now that military officials say they have destroyed six global positioning system jammers.

Air Force Major Gen. Victor E. Renuart Jr. said Tuesday in a press briefing at U.S. Central Command in Camp As Sayliyah, Qatar, that six GPS jammers "provided by another nation" were taken out of commission by U.S. forces.

"We destroyed one of the GPS jammers with a GPS weapon," Renuart said.

Renuart did not say specifically that the jammers were part of a shipment of materials supplied by Russian companies to Iraq, but the United States repeatedly has expressed its concern that Russia is letting the materials slip through in violation of decade-old U.N. sanctions.

Putin promised that he would investigate reports that Russian companies sold equipment, but took the opportunity to accuse Bush of creating a humanitarian crisis in Iraq.

In a Monday morning telephone call to Putin, Bush raised his concerns over reports that Russians are actually on the ground in Iraq teaching Iraqi forces how to use prohibited hardware like night vision goggles, GPS jammers and anti-tank guided missiles, White House spokesman Ari Fleischer said.

"President Putin assured President Bush that he would look into it. And President Bush said he looked forward to hearing the results," Fleischer told reporters. 

"We have concerns. Those concerns have been expressed at the highest levels, and these concerns have been expressed repeatedly over the last -- quite some little while," Fleischer added. 

A source told Fox News the GPS jammers in particular had slowed the bombing of Baghdad as the military has taken extra care to avoid hitting civilian targets.

Fleischer said senior U.S. government officials have repeatedly discussed with Russian counterparts over the past year how they can get the suspected companies to cut cooperation with the Iraqis. 

On Monday, Russian officials denied that Russia had sold any equipment to Iraq.

"We did not send any goods, including military ones, that violated the sanctions," Foreign Minister Igor Ivanov told reporters. "No fact supporting the Americans' anxiety has been found."

Ivanov said the United States had requested reports on the alleged illicit sales several times since October, with Russia making its most recent report on March 17. If there were any indication that Russian companies had shipped such goods, it would be investigated as a serious violation of Russian law, he added.

Fox News confirmed Sunday a report that three Russian companies were involved in military equipment sales. U.N. sanctions have allowed Iraq only to import goods approved by the oil-for-food program.

The State Department said it had raised the issue with senior Russian officials several times, particularly over the past two weeks, because the equipment could pose a direct threat to coalition forces. The United States even provided specific information regarding the transactions to Moscow in hopes the Russians would rein in the dealers.

Secretary of State Colin Powell told Fox News that he is not prepared to say that Russia is not being straight with the United States, but he is concerned about Russia's refusal to take action.

"Foreign Minister Ivanov assured me that with enough information and the right information, they would do something about it, but frankly, we have given them more than enough information so that should be able to find out the truth of this, and I am quite confident of our facts on this matter, very confident of our facts," Powell said.

Fleischer said that while the Russian action is troublesome, he did not blame the government, but Russian companies. However, officials note that the Russian government has to certify the export of materials like those cited, though they may have been shipped through a third country.

Ukraine has been named as one nation that has sold radar equipment to Iraq in violation of sanctions. Andrei Kokoshin, a former head of the Russian Security Council, said he was "100 percent" sure that Russian companies had not sold prohibited equipment to Iraq, but said the Ukraine may have re-sold materials first purchased from Russia.

Ivanov said that any companies that would have shipped such goods would be in violation of Russian law. He said Russia sent the United States a report as recently as March 17, discussing alleged illicit sales that have been the target of U.S. concern since October.

The U.S. government suspects that the Russians were hiding some jamming equipment in humanitarian aid flights to Baghdad, Fox News has learned. The boxes are about 3 ft. by 3 ft.

Moscow analysts discount the reports as rumor, and say the accusations are an attempt to discredit Russia for its refusal to back a war against Iraq.

"It seems to me it is just an attempt to put pressure on Russia and make the position of Russia in regard to Iraq softer," said Anton Khlopkov, an analyst at Moscow's PIR nonproliferation think tank.

Also Monday, Russian President Vladimir Putin called on Iraq to obey international conventions on the humane treatment of prisoners of war after 12 American soldiers were ambushed and believed captured or killed.

Putin told top Cabinet ministers that he had asked the Foreign Ministry "to appeal to Iraq with an urgent request to comply with these particular rules."

On Sunday, The Washington Post identified two of the firms that allegedly sold equipment as KBP Tula and Aviaconversiya, a Moscow-based company. It said KBP supplied antitank guided missiles and Aviaconversiya provided jamming devices.

Aviaconversiya director Oleg Antonov denied the claim, saying on Echo of Moscow radio that, "we have never delivered anything to Iraq."

He said the allegation was "conjecture resulting from the fact that tests of high-precision armaments revealed the total loss of their efficiency against our jamming."

The deputy director of Tula's instrument design office, Leonid Roshal, also denied the report, according to the news agency ITAR-Tass.

A spokesman for Russia's arms export agency, Rosoboronexport, said his organization "100 percent definitely had nothing to do with any sales and we have no information that such sales took place."

Rosoboronexport is the sole state intermediary for Russian military exports and imports.

A spokesman for the U.S. embassy in Moscow said that Moscow's response to the allegations "so far hasn't been satisfactory."

"We hope that the responsible Russian agencies will take our concerns seriously," he said.

Fox News reported in January that Iraq may have obtained as many as 400 electronic "jammers" that could throw America's smart bombs off their programmed path if the U.S. goes to war.

There was "real concern at the highest levels" at the Pentagon that Baghdad may have purchased the jammers from a Russian firm, a senior defense official said then.

If the smart bombs are diverted from their designated targets, they may hit non-military sites and cause civilian casualties — which could be used to Iraq's advantage.

The types of bombs whose courses may be altered by these jammers are called J-Dams — for "joint direct attack munitions," guided by global satellites. These are the military's GPS-guided bombs. Each one costs about $21,000 and has a maximum range of 15 miles. J-Dams made their combat debut in Kosovo in 1999.

It is estimated that 80 percent of U.S. weapons that would be used in a war with Iraq would be directed via satellites.

The Air Force is now trying to test similar jammers to see if those used by an enemy can really work on U.S. weapons.

Defense officials confirm the extensive use of GPS-guided munitions, including Tomahawks, JDAMs, and the EGBU-27 used to hit the Iraqi leadership compound on Wednesday night. These are all being used throughout the country. All of the munitions used in Baghdad have been GPS-guided.

Fox News' Teri Schultz and Wendell Goler and The Associated Press contributed to this report.