In 2016, the North Koreans released pictures of leader Kim Jong Un standing before a miniaturized nuclear device.
Moon said he wasn't offering unconditional co-operation.
The island is known for its white-sand beaches, and the Mariana Trench, the deepest ocean trench on the planet, isn't far away. Still, with just 210 square miles (543 square km) of land, it's about half the size of Los Angeles. And he's not going to threaten Japan. Thaad has a good record in tests, most recently destroying a target simulating a missile similar to the Hwasong-12 in July.
It is indeed ridiculous that the nation is unable to put a single anti-missile unit into full operation - a decision made more than one year ago - while the North has been upgrading its nuclear and missile technologies to the degree that it is believed to be capable of striking the US mainland with a nuclear-tipped intercontinental ballistic missile.
As he fishes, Martinez says North Korea remains at the back of his mind, despite his best efforts not to think about it. And he's pretty sure he's not alone.
"Because the western Pacific has American soil in it, then a couple hundred thousand Americans could get caught in the crosshairs", he added, referring to the possibility of a conflict in the region. The President would be told and consulted, but if the threat is imminent, the US military has the right to self-defense - and could make the decision. "Maybe it wasn't tough enough", Trump said.
On Thursday in Bedminster, New Jersey, where he is on a working vacation, Trump also declared the U.S. nuclear arsenal "in tip-top shape, and getting better, and getting stronger". "I'm not trying to overlook it or understate it. We understand the threats, but we also don't want to panic anybody, and we don't want to jump to conclusions based on rhetoric".
The U.S. set up the Naval Station in Guam in 1899, designating the whole island as a base. "And I think China will do a lot more", Trump said.
Previously it had said it would shoot down only missiles on course for Japan. The tree snakes have become huge pests and have wiped out many of the local birds and reptiles, according to the U.S. Department of Agriculture. As president, he ordered an assessment of the environmental impact of the THAAD system, which effectively delayed its deployment. It's followed by a classical music concert on Sunday.
Guam was claimed by Spain in 1565 and became a U.S. territory in 1898 during the Spanish-American War.
The threat sparked alarm in Tokyo and Seoul, which called on Pyongyang to desist from sabre-rattling.
Officials haven't raised the US territory's threat level even after Pyongyang laid out plans to strike near the island in the coming weeks, Guam Gov. Eddie Calvo said. It has a strategically located U.S. air base, a Navy installation that includes a submarine squadron, a Coast Guard group and roughly 6,000 U.S. military service members.
Jim Mattis, defence secretary, also emphasised US power, saying Pyongyang's actions "could lead to the end of its regime and the destruction of its people".