U.S. President Donald Trump¡¯s surprisingly restrained reaction to North Korea¡¯s latest ballistic missile test has left many observers wondering what his next move will be. Trump has publicly declared that North Korea¡¯s goal of developing a nuclear-capable missile that can reach the United States ¡°won¡¯t happen.¡± But what, specifically, will he do to prevent it?

Some might advise the Trump administration to launch pre-emptive strikes on North Korea¡¯s nuclear facilities. But this is a dangerous and ineffective option, because North Korea would then likely retaliate against South Korea. South Koreans do not want to risk a war, so a U.S.-provoked attack by North Korea would be catastrophic for the U.S.-South Korean alliance.

Moreover, North Korea recently developed missiles with solid-fuel engines, which can be stowed away until just before they are launched, making it technically difficult to identify the right targets ¡ª and the right times to strike them.