South Korean Acting President Hwang Kyo-ahn on Tuesday warned of "greater provocations" from the DPRK. The possibility of the DPRK conducting a military test is exacerbating tensions. 

Hwang has ordered the army and the foreign and defense ministries to heighten the security alert concerning the DPRK, based on the strong military alliance between the US and South Korea.

Besides the US deployment of the Carl Vinson battle group to waters off the Korean Peninsula, about 3,700 armed forces personnel from the US and South Korea are scheduled to take part in a joint exercise near South Korea's Pohang city from April 10 to 21. The drill will focus on alliance logistics capabilities in air, land, sea and space, as well as on information environments.