Updated

President Barack Obama served notice Wednesday that he would punish those trying to disrupt the political transition in Yemen, a strategically important Middle Eastern nation, by freezing their U.S.-based assets.

An executive order gives the Treasury Department to power to act against those said by the White House to "threaten the peace, security and stability" of Yemen.

The order gives Yemen's new president, Abed Rabbo Hadi, an additional tool to sweep out relatives and cronies of authoritarian leader Ali Abdullah Saleh who are refusing to relinquish their political or military posts. Hadi issued a decree last month ordering the holdovers to leave, and the U.S. presidential order could target the assets of anyone who fails to comply, according to a senior administration official, who spoke on condition of anonymity to describe the policy.

"We've had concerns about spoilers," State Department spokeswoman Victoria Nuland told reporters. "We've had concerns about foot-draggers. We've had concerns about actual opposition from various different groups and so this is a new tool that we can use to make our views known if that continues."

She said the order was meant to send "a message to those who are trying to block transition that we have this tool to use against them, and that they should think again about the policies that they are pursuing," she said.

Officials fear that instability in Yemen, a critical counterterrorism partner for the U.S., will provide an opening for al-Qaida affiliated groups to expand their influence. The White House says Obama took the step because he believes the legitimate aspirations of the Yemeni people cannot be addressed if political progress stalls.

Yemen has been a launching pad for attacks against the U.S. by the Yemen-based al-Qaida in the Arabian Peninsula. Last week, The Associated Press disclosed that the CIA thwarted an ambitious plot by al-Qaida in the Arabian Peninsula to destroy a U.S.-bound airliner using a bomb with a sophisticated new design.

The Pentagon also announced last week that it was sending military trainers back to Yemen for "routine" counterterrorism cooperation with Yemeni security forces amid an intensified battle against terrorists. The training program in Yemen was suspended last year after then-President Ali Abdullah Saleh was badly injured in a militant attack.

Under a U.S.-backed transition plan, Saleh stepped down earlier this year after more than 30 years in power, clearing the way for his vice president Hadi, to assume control of the government. U.S. officials allowed Saleh to come to the U.S. for medical treatment during the transition to help ensure it went off smoothly.

With Saleh back in Yemen, some U.S. officials have expressed concerns that he could try to wield power from the sidelines through his network of relatives and allies.

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Associated Press writers Kimberly Dozier and Matthew Lee contributed to this report.