Quoting a Pentagon official, the Wall Street Journal reports that Washington has conducted a site survey for possible deployment locations in South Korea for its Theater High Altitude Area Defense, or THAAD.
No final decision has been made yet on the system which is designed to intercept a diverse range of missiles.
South Korean officials have indicated that Seoul would prefer to develop its own defenses rather than taking part in the U.S.-led system.
With that in mind, the report quotes the Pentagon official as saying that the U.S. could deploy the THAAD system to South Korea for a temporary period, and then replace it with another system purchased by Seoul.
It could also let Seoul buy its own missile defense system.
The Vice Chairman of the U.S. Joint Chiefs of Staff James Winnefeld, meanwhile, is calling for better regional missile defense cooperation between South Korea and Japan.
Speaking at a seminar in Washington Wednesday, Winnefeld emphasized the importance of developing a regional missile defense system between its main allies, to effectively counter North Korean threats.
U.S. Congress also passed a bill last week that calls on the Defense Secretary to assess the opportunities to strengthen ballistic missile defense cooperation among Seoul, Tokyo, and Washington.
This is raising pressure on South Korea to join the U.S.-led missile defense system.
Given Seoul's reluctance to join the U.S.-led system and the development of its own missile defense system, the issue is expected to be one of top agenda items at an upcoming trilateral meeting between the defense chiefs of South Korea, the U.S., and Japan.
The officials are scheduled to meet this weekend on the sidelines of the Asia Security Summit in Singapore.
Park Ji-won, Arirang News.