What did the aircraft carrier sail towards volatile waters for?

The aircraft carrier USS George Washington sailed toward waters off the Korean peninsula Wednesday for planned military exercises with South Korea in a show of force designed to deter a further escalation of hostilities with North Korea. The exercises were billed as defensive in nature and were a more measured response than the retaliation initially urged by South Korea after North Korea’s shelling of a South Korean island Tuesday, the most serious act of hostility since the end of the Korean war.
    The shelling of Yeonpyeong Island killed four people—including two civilians—and left an entire region fearful of an all-out war. The U.S. military said the military drills demonstrate the strength of Washington’s alliance with Seoul and "our commitment to regional stability through deterrence".