The United States must confront Russia for providing weapons to the Taliban for use against American-backed forces in Afghanistan, top US military officials said today. At a news conference with Defense Secretary Jim Mattis at his side, Gen. John Nicholson, the American commander in Afghanistan, wouldn't provide specifics about Russia's role in Afghanistan. But said he would "not refute" that Moscow's involvement includes giving weapons to the Taliban. Earlier today, a senior US military official told reporters in Kabul that Russia was giving machine guns and other medium-weight weapons. The Taliban are using the weapons in the southern provinces of Helmand, Kandahar and Uruzgan, according to the official, who briefed journalists on intelligence information on condition of anonymity. Russia denies that it provides any such support to the Taliban, which ruled Afghanistan until the US-led invasion in 2001. Russia says contacts are limited to safeguarding security and getting the hard-line religious fundamentalists to reconcile with the government \u00e2\u20ac\u201d which Washington has failed for years to advance. Russia also has promoted easing global sanctions on Taliban leaders who prove cooperative. Also Watch: Asked about Russia's activity in Afghanistan, where it fought a bloody war in the 1980s and withdrew in defeat, Mattis alluded to the increasing US concerns. "We'll engage with Russia diplomatically," Mattis said. "We'll do so where we can, but we're going to have to confront Russia where what they're doing is contrary to international law or denying the sovereignty of other countries." "For example," Mattis told reporters in the Afghan capital, "any weapons being funneled here from a foreign country would be a violation of international law."