Updated

Gen. Kenneth "Frank" McKenzie, the commander of U.S. Central Command, told reporters Tuesday he doubted that intelligence of Russian bounties to Taliban fighters actually led to deaths of U.S. troops in Afghanistan, saying, "I found it very worrisome, I just didn't find that there was a causative link there."

McKenzie, the top U.S. general in the Middle East, told news agencies including The Associated Press and ABC News, "The intel case wasn't proved to me -- it wasn't proved enough that I'd take it to a court of law -- and you know that's often true in battlefield intelligence."

Some U.S. intelligence officials have said information that Russia offered bounties to Taliban militants for killing American troops was included in an intelligence brief for President Trump in late-February. The White House, however, has denied Trump was briefed at that time, arguing that the intelligence was not credible enough to bring to his attention.

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McKenzie noted that while he could not find any credible links between payments and U.S. soldier deaths, the intelligence was not always definitive.

McKenzie also said Russia has been a threat in Afghanistan for years, and many reports have uncovered Russian backing of Taliban forces. But, he also noted that whether or not the Taliban was receiving aid from Russia, they have been and remained a "high force protection threat."

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"Over the past several years, the Taliban have done their level best to carry out operations against us, so nothing is practically changed on the ground in terms of force protection," McKenzie told reporters.

The general explained that tensions between the U.S. and Russia have been high over Afghanistan because of Russia's defeat there, back in the 1980s, and Russia would use any opportunity it could to "throw sand in our gears" to make life uncomfortable.

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"We should always remember the Russians are not our friends, they are not our friends and they are not our friends in Afghanistan and they do not wish us well," McKenzie said. "We just need to remember that at all times, when we evaluate that intelligence."

Fox News' Jennifer Griffin and The Associated Press contributed to this report.