North Korea said under the plan, four Hwasong-12 rockets would fly over Shimane, Hiroshima and Koichi prefectures in Japan, hitting waters 19 to 25 miles from the island, the Associated Press reported.
Spain claimed Guam in 1565, more than 40 years after Ferdinand Magellan landed on the island.
Guam is home to U.S. Naval Base Guam and the Andersen Air Force Base. Since the end of the Spanish-American War in 1898, the largest and southernmost island in the Mariana Islands archipelago has been an essential part of US power projection.
Gaminde's remarks comes after North Korea announced earlier on Thursday that the nation has a detailed plan for a missile strike near Guam, where about 7,000 United States troops are stationed, using four intermediate-range ballistic rockets. Their location in a USA territory means its military is just hours from potential flashpoints in the western Pacific.
Here's a closer look at Guam and its role in the USA and North Korea's ongoing war of words.
Like other US territories, Guam has a sometimes complicated relationship with the USA mainland but many across the island say despite the threats and concerns they feel reassured and protected by the military - especially in times of tense, geopolitical sparring.
Former President Clinton squats as he examines the names of World War II war dead on a wall at the War in the Pacific National Historical Park on the island of Guam in 1998.
"I don't see a military solution and I don't think it's called for", said German Chancellor Angela Merkel. Along with a bigger set of manoeuvrs held every spring, the exercises are routinely met by strong condemnation and threats of countermeasures from North Korea.
'Can you believe' McConnell couldn't repeal, replace ObamaCare?
The attacks are a risky approach considering Trump's slumping job approval ratings among his most fervent supporters. But they continue to butt heads with a White House that's unhappy with where they left the health care debate.
The U.S. keeps a Naval base and Coast Guard station in the south, and an Air Force base in the north that saw heavy use during the Vietnam War.
For decades, Guam has been a critical asset for the USA military, housing 6,000 troops and strategic bombers capable of carrying nuclear weapons.
A statue of Guam hero Ricardo Bordallo is pictured at the entrance of the Governor's Complex on the island of Guam, a U.S. Pacific Territory, August 10, 2017. President William McKinley ordered Guam to be ruled by the U.S. Navy. Guam was also a refueling and transfer spot for people heading to Southeast Asia, and many refugees fleeing Saigon were evacuated through Guam.
Resident Isaac Camacho, 19, says he feels Guam's relationship with the US mainland is "a little misunderstood on their part".
In August past year, the North's Foreign Ministry warned that all USA military bases in the Pacific including Guam would "face ruin in the face of all-out and substantial attack" by the North's military.
Asked about Trump's tough posture, Guam Governor Eddie Calvo said he agreed with sending a clear message to North Korean leader Kim Jong Un, who has ramped up his country's tests of missiles and nuclear bombs.
In that case, Onedera said that Japan could exercise the right to collective self-defense and intercept the missiles.