With the country's attention focused on Al Qaeda's increasing strength and operations in Yemen, a Republican congressman again is asking President Obama about the wisdom in sending terror suspects from Guantanamo Bay to the Arabian Gulf state.

In a letter to the President, U.S. Rep. Frank Wolf (R-Va.) cited the recent release of Guantanamo detainees to Yemeni custody and said continuing the practice threatened national security.

"It is unconscionable that your administration would release terrorist detainees back into the clutches of al Qaeda in Yemen, Somaliland and Afghanistan as was done earlier this month," Wolf wrote. "These dangerous detainees were released under a cloak of secrecy and the American people were not informed until these individuals walked free. Your administration still has not provided information on their past terrorist activities. These releases are reckless and the administration's continued concealment is a danger to the security of America."

Umar Farouk Abdulmutallab, the Nigerian man who smuggled explosives onto a Detroit-bound plane from Amsterdam on Christmas Day, reportedly had been in Yemen since August. Other reports say he has told officials there are others just like him in the Gulf state who are preparing attacks.

It's the sixth letter Wolf has sent to the President since October raising concerns about sending Guantanamo detainees to "Yemen and other dangerously unstable countries." (See them all here.)

Wolf, the ranking Republican on an appropriations subcommittee dealing with the Justice Department, tried to amend the 2010 budget to require unclassified notifications about impending detainee releases. The White House opposed the amendment, which failed.

Wolf, who also was critical of the Bush administration on some security issues, isn't backing off.

"This is important to national security," Wolf hand wrote across the bottom of the letter. "Please stop the releases."