How do Micronesia, Guam and the Northern Marianas give the US "dominance in the Pacific", according to experts"?

Question

The NBC News article Why is this tiny Pacific Ocean nation getting VIP treatment in Beijing? says:

David Panuelo, president of the Federated States of Micronesia — a nation of some 600 islands and islets with a population of just 113,000 — is this week visiting China, where President Xi Jinping and other top officials have come out in force to lavish him with attention and offers of economic cooperation deals.

Micronesia, along with the Marshall Islands and Palau, are bound by a "compact of free association" with the United States which gives Washington exclusive military control of the countries’ land, airspace and surrounding waters in exchange for hundreds of millions of dollars in assistance and other privileges. But in recent years, Micronesia has increasingly turned to Beijing for much needed investments and economic aid.

Together with Guam and the Northern Marianas, these countries ensure that Washington controls more than 3 million square miles in the western Pacific — about the size of the continental U.S. — which underpins American dominance in the Pacific, according to experts.

But the pact and its funding program are set to expire in 2023-2024, and the outcome of negotiations to extend it is uncertain.

Do the territorial waters extending around all of the islands of Micronesia, Guam and the Northern Marianas add up to anything close to "3 million square miles in the western Pacific"?

How do the discussed agreements with these countries allow the US to "control" that much area; what kind of control is referred to here? Is it just a poor synonym for "military dominance"?

Answer 1

The reference is for military control, not economy issues are related to this.
To explain this we must return some decades back, to World War II. When USA took Marianas islands from Japan, two of them (Guam and Tinian) are big enough to have airfields. No other islands around thousands of miles have airfields. Hence, who controls those airfields can also exercise control over the sea around. Only Wake island and Palaos island are big enough to have airfields as well.
From Tinian USA sent bombers against Japan during WWII, including the planes carrying the atomic bombs.
Check Guam in Google Earth, it includes not only a civilian airfield, it also has nice a military airfield with some planes visible.
While having control of those islands, USA can say hello to China.