Pentagon: The THAAD deployment to South Korea is only the first step if North Korea doesn't behave

WASHINGTON, DC - Critics of Seoul and Washington's decision to deploy America's most advanced missile-defense system to South Korea are pointing to North Korea's latest submarine-launched ballistic-missile (SLBM) test as retaliation.

In order to counter North Korean threats, such as Wednesday's launch of a presumed KN-11 missile, a Terminal High Altitude Area Defense (THAAD) battery is expected to be operational in South Korea by the end of 2017.

Earlier this month, China - Pyongyang's closest ally - said that since the US agreed to equip South Korea with the unique defense system, the North's missile tests have expanded and are poised to increase.

"We're not going to predict the future but we would welcome steps by North Korea to ease tensions and to not take these kinds of provocative actions," Pentagon spokesman Peter Cook told Business Insider during a press briefing.

"We would certainly hope that we don't have to expand and take additional steps. But the reality is what it is, and we are taking the steps that allies should take to try and coordinate and work closely together to try and address the threat that we see right now from North Korea."

Pressure to deploy THAAD to the region was spurred after Pyongyang tested its fourth nuclear bomb on January 6 and then launched a long-range rocket on February 7.