The Trump administration last week released its Missile Defense Review (MDR). It acknowledges the mounting threat posed by countries such as North Korea and Iran, as well as the modernization of strategic forces in China and Russia. As a solution, the report harkens back to the vision of President Ronald Reagan, who sought to protect the United States from missile attack with an impenetrable shield. "Star Wars" was dismissed as both fantastical and dangerous: Its goals exceeded the capabilities of existing technology and threatened an arms race between the U.S. and its adversaries. That constraint and that danger persist.

Congress requires every administration to detail its missile defense strategy, plans and priorities; this document provides insight into the government's security and defense thinking. The MDR should have been published a year ago but was delayed as the Pentagon sought to keep pace with a changing international environment and the president's evolving thinking. The delay means that much of the MDR's content is known; the contours of the strategy have been evident in budgets and speeches by senior officials. Yet the language of the MDR remains striking. It notes that the security environment is "more complex and volatile than any we have experienced in recent memory," with potential adversaries "investing substantially" in missile capabilities. They are increasing the capabilities of existing systems, adding new and unprecedented types of missile capabilities, and integrating offensive missiles into their planning.

The report identifies North Korea as an "extraordinary threat" to the U.S., with investments in nuclear and missile capabilities to be able to threaten the U.S. homeland. Pyongyang has accelerated efforts to field missiles that can threaten U.S. forces and those of its allies — including Japan — and warns that nuclear weapons could be used in the event of a conflict in Asia. According to the report, "China seeks to displace the United States in the Indo-Pacific region and reorder the region to its advantage," and its nuclear and missile capabilities "play an increasingly prominent role" in that effort. It uses those capabilities to also deny the U.S. the ability to protect is allies and partners in Asia; the report adds that China's conventional ballistic missiles are a key part of that strategy.