Ri Yong Ho

US Secretary of State Rex Tillerson is wasting time trying to negotiate with North Korean leader Kim Jong-un, US President Donald Trump said on Twitter.

"I told our lovely Secretary of State, Rex Tillerson, that he was wasting time to seek talks with the little 'Rocketman', save energy, Rex, we will do what we have to do," wrote the US leader.

By James Stavridis*

As the doomsday rhetoric intensifies between two untested and inexperienced leaders in Pyongyang and Washington, the risk of actual combat is rising.

North Korea appears to have boosted defenses on its east coast, South Korea's Yonhap news agency said yesterday, after the North said U.S. President Donald Trump had declared war and that it would shoot down U.S. bombers flying near the peninsula.

North Korean Foreign Minister Ri Yong Ho said Monday the DPRK has every right to "take countermeasures against the United States, including shooting down American strategic bombers outside the DPRK's airspace, as Donald Trump declared war" on the Asian country.

Ri stressed that the the "declaration of war" means that all options will be on the table for the North Korean leadership.

North Korea’s foreign minister said on Monday that President Donald Trump had declared war on North Korea and that Pyongyang reserves the right to take countermeasures, including shooting down U.S. bombers even if they are not in its air space.

North Korea said on Friday it might test a hydrogen bomb on the Pacific Ocean after U.S. President Donald Trump vowed to destroy the country, with leader Kim Jong Un promising to make a "mentally deranged" Trump pay dearly for his threats, Reuters reports.