The US on Wednesday morning test-launched an intercontinental ballistic missile to show the readiness of the country's nuclear foces.
The test launched at 1.13am local time from Vandenberg Space Force Base in California, the base said on Twitter.
Describing the test as "routine", the Pentagon on Tuesday said it was scheduled far in advance and that Russia and other countries were notified.
“There will be an operational test launch of an Air Force Global Strike command unarmed Minuteman III intercontinental ballistic missile early tomorrow morning, September 7, from Vandenberg Space Force Base in California,” Pentagon spokesman Pat Ryder said on Tuesday.
The purpose of Wednesday's test was "to demonstrate the readiness of US nuclear forces”, Mr Ryder said.
The US successfully carried out a test launch of a Minuteman III missile on August 16 after it was delayed several times because of escalating tensions over Ukraine and Taiwan.
The missile carried a test re-entry vehicle, which in a conflict could be armed with a nuclear warhead.
The re-entry vehicle travelled about 6,760 kilometres to the Kwajalein Atoll in the Marshall Islands in the western Pacific.
Mr Ryder said the two tests were scheduled long ago and occurred close together because of the first test's postponement.
US Himars multiple launch rocket system - in pictures
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A High Mobility Artillery Rocket System (Himars) rocket fired by US forces during live-fire exercises in the Philippines. Reuters -
The Himars is a light multiple rocket launcher developed in the late 1990s. EPA -
Himars rockets are fired during US military exercises in Morocco. AFP -
Ukrainian soldiers ride on a vehicle carrying a rocket launcher in eastern Ukraine. AFP -
A vehicle fires the Himars during combat training in Yakima, Washington state. The Olympian / AP -
A soldier stands in the ruins of Mariupol's theatre, destroyed in Russian shelling. AFP -
A Himars rocket launcher displayed at the 2021 Dubai Airshow. AFP -
A Ukrainian soldier stands outside a school hit by Russian artillery in the village of Zelenyi Hai. AFP -
US military personnel stand by a Himars vehicle during a defence show in Saudi Arabia. AFP -
A US Himars is unloaded during military exercises in Latvia. EPA -
Ukrainian soldiers embedded in a trench on the front line in the Lugansk region. AFP
Agence France-Presse contributed to this report
