The system was agreed upon by the USA last year, but hesitation from China led South Korean officials to put it on the backburner.
However, China raised objections to the deployment saying the anti-missile system's radar could penetrate its territory.
This, along with an increased focus on cyber warfare and benefits for veterans are part President Donald Trump's plan for "Making Our Military Strong Again".
Leading analysts in both South Korea and the US believe Pyongyang is ready to challenge the Trump administration with a provocation in the coming days - Seoul officials last week revealed North Korea appears to be preparing an intercontinental ballistic missile test.
The policy announcement came a day after reports that Pyongyang was readying a test of an upgraded intercontinental ballistic missile prototype. North Korea carried out at least four Musudan tests from the same site a year ago. "They are also miniaturizing nuclear weapons".
North Korea has conducted a series of missile and nuclear tests in spite of United Nations sanctions.
Within South Korea, voices opposing the installation have grown louder, with some opposition candidates pledging to scrap the agreement if they win a presidential election due this year.
"The U.S. Navy continually seeks every occasion to strengthen relationships and interoperability with participating allies and partners while further developing maritime capabilities and capacity", said Lt. Josh Kelsey, a spokesman for the U.S. Naval Forces Korea.
The North and South are technically still at war because their 1950-53 conflict ended in a truce, not a peace treaty. "We have engaged in diverse cooperation since the beginning of our diplomatic ties", and added that while there were some concerns, they needed more time to address them.
Hwang was speaking in place of President Park Geun-hye, who has been impeached by parliament amid an influence-peddling scandal and stripped of her powers as she awaits a court decision on her fate.
The plan has also angered Beijing, which has imposed a string of measures seen in the South as economic retaliation, including effectively barring K-pop stars from performing on the mainland and not authorising South Korean airlines to operate charter flights between the countries.