The US testing signals that Washington is seeking to bolster its abilities to counter Chinese military and economic expansion into the energy-rich waters and vital trade routes of the Indo-Pacific.
Such weaponry could be game-changing for Guam, the tiny US territory roughly the size of Leeds, which hosts about 190,000 American civilians and military personnel.
The remote island lies about 1,800 miles from China, making it the closest US outpost to the rival superpower. It is known as the "tip of the spear" of US defence.
American military bases, including Andersen Air Force Base and the Naval Base Guam, occupy nearly 30 per cent of the island and are critical to the US Indo-Pacific policy.
The island also plays a significant role in Washington's military strategies towards China, the Korean Peninsula, and potential flashpoints including the South China Sea and Taiwan.
Last September, China's PLA Air Force released a video showing nuclear-capable H-6 bombers carrying out a simulated attack on Guam's air force base.
In 2017, the island was also the target of North Korean threats of missile strikes and "enveloping fire".
The dome was developed by Israel's Rafael Advanced Defense Systems Ltd, in cooperation with Raytheon Technologies Corp, and is only designed to destroy short-range rockets and artillery up to 64km away, meaning the US must also pursue separate plans to beef up its Pacific defences.
"If we can't defend Guam - the airbase and the other things there - it's really hard to project power into the Pacific," Tom Karako, director of the Missile Defense Project at Washington's Centre for Strategic and International Studies, told the Wall Street Journal.
The US Congress ordered the purchase of two Iron Dome systems for around $373 million ($528 million) in 2019.
In March this year, the US Indo-Pacific command presented a $27.3 billion strategic plan for new missiles, air defences, radar systems, staging areas, intelligence-sharing centres, supply depots and testing ranges throughout the region.
Defence experts have long touted the value of spreading US military personnel and assets across a wider range of Pacific Island bases as the US seeks to expand its military footprint and build a more effective deterrent against Chinese military power.
Heino Klinck, former deputy assistant secretary of defence for East Asia, said the US strategy was focused on "places not bases" to respond to the growing Chinese military threat in the West Pacific and to complicate the People's Liberation Army calculus.
