The US, South Korea and Japan began a two-day missile tracking drill Tuesday amid rising tensions with North Korea.
The exercises, South Korea's military said, is in preparation for any missile or nuclear threats from the North.
The drill will be held in waters off the coasts of South Korea and Japan, the South Korean military said in a statement.
Included in these drills were the Aegis destroyer Yulgok Yii of South Korea, USS Stethem and USS Decatur Aegis destroyers from the States and a JDS Kirishima destroyer from Japan.
The exercise will have the warships detect and track a target while sharing information.
The drills have been taking place every few months since that agreement.
The United States Air Force will put its ageing fleet of nuclear-capable B-52 bombers on 24-hour alert for the first time since the end of the Cold War, according to its chief of staff.
Amid rising tensions with North Korea and a resurgent Putin-led Russia, General David Goldfein told Defense One that the strategic bomber force will be ready at a day's notice for the first time in 26 years.
Adapting to the 'reality of the global situation', Goldfein's order would see B-52s readied at Barksdale Air Force Base in Louisiana and armed with nuclear weapons - something not seen since 1991.
In response to the news, North Korea said President Trump was 'overheated with a war fever' and branded him a 'hooligan' and a 'lunatic'.
The government-owned news agency KCNA lashed out in a furious tirade: 'Dignitaries of White House, and State and Defense Departments of the US are having a hard time cooling Trump overheated with a war fever, but only the south Korean puppet forces are fanning up the lunatic fingering a nuclear button.
Barksdale - the home of the 2D Bomb Wing and Air Force Global Strike Command - is currently being refurbished in anticipation of the change in defense posture to allow the bombers to 'take off at a moment's notice'.
This is the latest defensive move from the US military, matching the bellicose threats that President Trump has posted on Twitter, putting North Korea, Iran and other American enemies on notice he will use the might of the armed forces.
RIA Novosti said individual warheads could have yields up to 750kt and that RS-28 launch silos would be built to withstand seven nuclear strikes.
Millions of residents still don’t have access to electricity or proper health care, and bacteria in the water have exposed many people to disease. And calls for help have gone unanswered besides the few willing to travel to the devastated island privately. Senator Martin Heinrich (D-NM) along with a handful of other lawmakers are calling on the federal government to continue to provide aid to the post-apocalyptic ravaged territory.