Samsung's new Galaxy smartphone is expected to pose a serious challenge to Apple's iPhone.
Nonetheless, the sanctions pose a serious challenge for the United States.
Still, there are some highly dangerous and violent prisoners who pose a serious challenge to prison discipline and safety.
Mr. Saleh's sudden departure stunned Yemenis and could pose a serious challenge for the United States, which has been deeply concerned about Yemen's rising chaos, analysts say.
Still, there was some way to go before China's overall military capability, including its nuclear arsenal, could pose a serious challenge to the United States.
The radical union and Mr. Malema pose a serious challenge for South Africa, which has enjoyed a remarkably peaceful transition from white rule to multiracial democracy.
A swift election would make it hard for Japan's array of smaller "third" parties to band together and pose a serious challenge.
By late 2013 ISIL had begun to pose a serious challenge to the Iraqi government's control in western and northern areas of the country.
Officials will be watching to see whether Pakistan's fractured opposition, including Ms. Bhutto and her political party can unite and pose a serious challenge to General Musharraf.
What's the most likely scenario, in your opinion, for an alternative party to gain momentum and pose a serious challenge to the Kremlin?
He has broad support and would pose a serious challenge in the June elections to President Mahmoud Ahmadinejad, whose aides have said he will seek re-election.
