The U.S. general warned that even one stray North Korean missile could wreak havoc on South Korea because of the high population density here. He also stressed the need "to present a sufficient combination of capabilities that is known to an adversary in both defensive and offensive aspects so that deterrence actually occurs."

Brooks joins a growing chorus of hawkish voices in the U.S. calling for preemptive strikes against North Korea if it continues its nuclear and missile programs. Brooks said existing defenses are "insufficient" in dealing with the North Korean missile threat.

U.S. Forces Korea Commander Vincent Brooks has called for greater capability to target and destroy North Korean missile bases. Addressing the Association of the United States Army in a video call on Tuesday, Brooks said the proliferation of low-cost missiles that can be used to threaten the U.S. requires a "layered" approach to missile defense.

Brooks is not the only U.S. government official touting the need for preemptive strike capabilities. New U.S. Secretary of State Rex Tillerson on Wednesday vowed to come up with a "new approach" to dealing with North Korea that includes military measures, while Senate Foreign Relations Committee Chairman Bob Corker asked a hearing on North Korea last week whether the U.S. needs to prepare for a preemptive attack on the North's putative intercontinental ballistic missiles.

The fact that hawks like National Security Adviser Michael Flynn and Defense Secretary James Mattis now wield the power in American defense policy make such comments much more resonant than before U.S. President Donald Trump was inaugurated.

In the past, the prospect of preemptive strikes had been mentioned primarily by U.S. analysts on a theoretical basis, but now they are being touted as viable options by government officials and lawmakers.

But pundits say a number of conditions need to be met to justify a strike at the risk of a full-blown war. First, the North operates a number of secret uranium enrichment facilities in addition to the Yongybon nuclear facility, but U.S. intelligence officials do not know where they are. Also, long-range missiles such as the KN-08 or KN-14 ICBMs are transported on mobile launchers), which make them extremely hard to locate.

The aim of a preemptive strike would be to disable North Korea's nuclear and missile capabilities completely, so accurate and detailed intelligence is critical. Also, steps would have to be taken to minimize the risk of U.S. and South Korean casualties if a full-blown war breaks out.

Kim Yeol-soo at Sungshin Women's University said, "If the U.S. launches a strike, it would have to ask Seoul first and I wonder how prepared the government here is to allow that."

And Park Won-gon at Handong Global University said, "Trump considers the financial costs of everything. Would he be willing to foot the huge bill of waging war?"