[Personal Analysis] If South Korea doesn't deploy THAAD, what are the alternatives?

Based on my understanding, one of the main reasons for the deployment of THAAD is due to the increasingly nuclear threat that causes the national security of South Korea. Other than THAAD, are there any alternatives that could be done? 

Following are some of the alternatives of THAAD will I personally feel will be feasible.

   1) Call for a stronger measure from China and Russia along with the existing sanctions

The UN Security Council resolution (2270) regarding sanctions on North Korea is in effect, encompassing transaction of shipping service, armed goods including WMD and financial support. However, there is a constant capital interaction at a market between North Korea and China where several items are still being imported, not to mention the smuggling trade. Therefore, sugguestion can be made to  China in taking a substantive measure that blocks the capital inflow to North Korea, which will end up supporting the development of its arsenal. Moreover, Russia’s “Najin-Hasan Project” may be asked to be stopped for the same reason.

   2) Resume of the Six-Party Talk

Ideally, all relevant parties seek to resolve North Korea’s nuclear issue in a peaceful manner. China and Russia in particular, strongly suggest to resume the Six-Party talk to persuade Pyongyang, asserting the absence of other options. For the past six meetings, the Six-Party Talk did make a progress in solidifying and integrating the will of participating countries to denuclearize Pyongyang. However, the practicality issue remains in question. Hence considering today’s situation,  six-party talk can be resume even without North Korea to facilitate the enforcement mechanism.

   3) Strengthening KAMD (Korea Air and Missile Defense)

The Republic of Korea Force already possesses its own missile defense system which is only confined to provide protection at terminal stage of missile attack. Instead of deploying the THAAD that guarantees higher probability of defense, South Korea may take a leverage role for receiving financial and technical support from China and Russia to enhance the existing system of KAMD. The support not only includes increasing the number of intercepting missiles but also upgrading the altitude capability of the system.