Anchor: KBS spotted South Korea's top nuclear envoy arriving in Washington just 32 hours after North Korea demolished an inter-Korean liaison office. With U.S. security experts calling for a show of American military might, special representative Lee Do-hoon is expected to discuss the current situation with key Washington officials. However, he refused to discuss the nature of his unannounced visit. 
Kim Bum-soo has more. 

Report: 

[Sound bite: Lee Do-hoon - Special Representative for Korean Peninsula Peace and Security Affairs]
"I cannot talk now."
(Reporter: Just tell us as much as you can discuss.) 
"I am sorry."

South Korea's top nuclear envoy Lee Do-hoon arrived at Washington Dulles International Airport on Wednesday, just a day and a half after North Korea blew up an inter-Korean liaison office.

As KBS reporters approached, Lee refused to discuss the purpose of his unannounced visit.

He is expected to meet White House National Security Adviser Robert O'Brien and Deputy Secretary of State Stephen Biegun, who is still in charge of negotiations with Pyongyang. 

In a notice sent to Congress, U.S. President Donald Trump on Wednesday extended existing U.S. sanctions on North Korea for another year, citing the continued nuclear and missile threats posed by the regime.

The U.S. State Department expressed disappointment over the North's hostile actions, and called on Pyongyang to refrain from further counterproductive actions.

Former U.S. security and defense officials, including retired general Vincent Brooks, former commander of South Korea-U.S. Combined Forces Command, suggested it's time to warn Pyongyang that it's crossing a line.

[Sound bite: General(Ret.) Vincent Brooks - former Commander of South Korea-U.S. Combined Forces Command (June 17 CSIS online forum)]
"We would be seeking ways to increase pressure with the military instrument while at the same time not foreclosing on the necessary engagement that North Korea seems to have closed the door on but really hasn't yet."

Brooks added that the ways to increase military pressure would mean things like announcing that the U.S. will lift the embargo on bringing strategic assets onto the Korean Peninsula, which hasn't happened since spring 2018.

[Sound bite: General(Ret.) Vincent Brooks - former Commander of South Korea-U.S. Combined Forces Command (June 17 CSIS online forum)]
"We're talking about nuclear-capable bombers, F-35 Joint Strike Fighters, aircraft carriers, nuclear submarines, all these things that are options to simply show presence. And I would submit to you by bringing these back in. It would agitate North Korea. And North Korea, I believe, needs to be agitated right now as a result of this, so that they feel that they may have overstepped, and that becomes the first effort in them self regulating a degree of deterrence once again."  

During a virtual seminar hosted by the Hudson Institute, Trump's former national security adviser Herbert McMaster said Washington should demonstrate its ability to respond to North Korea's threat "militarily," calling for robust military exercises with South Korea in August.  
Kim Bum-soo, KBS World Radio News.