Afghanistan ? The U.S. military is seeing early signs that al-Qaida may be stepping up its activities in Afghanistan, a senior defense official revealed for the first time Monday as Secretary Robert Gates made his third trip to this country.

Gates said he has not yet seen data on any uptick in al-Qaida activity, but he said increasing levels of violence in the country are a concern and he plans to talk about it with other defense leaders from NATO nations operating in Afghanistan.

“I’m not worried about a backslide as much as I am (about) how we continue the momentum going forward,” Gates told reporters in Djibouti on Monday just before he left for Kabul. “One of the clear concerns that we all have is that in the last two or three years there has been a continuing increase in the overall level of violence.”

As Gates headed to Kabul, U.S. officials also said they are now considering the possibility of providing arms to local tribes in Afghanistan, along with training, equipment and other support. The effort would be modeled after successful efforts in Iraq to empower the locals to police their own neighborhoods.

While no decisions have been made, officials said the plan is under review.