The three flattops - USS Ronald Reagan, USS Nimitz and USS Theodore Roosevelt - entered the operational area, called the Korea Theater of Operations (KTO), for the four-day maneuvers slated to end Tuesday.
This comes as Trump said on Thursday that he wants Russia's help in getting North Korea to give up its nuclear weapons.
Also on Saturday, the US and South Korean navies launched four days of joint drills off the east coast of South Korea.
North Korea has dominated Trump's trip, which has so far swept in Japan, South Korea, China and Vietnam.
It's the first time since a 2007 exercise near Guam that three US carrier strike groups are operating together in the Western Pacific, according to the US Navy's 7th Fleet.
The exercise comes after the two countries agreed in talks between their respective defense ministers last month to expand the rotational deployment of USA strategic military assets to the Korean Peninsula to better cope with North Korean provocations. That, according to Pyongyang, only encourages North Korea to "speed up" completing its nuclear armed forces.
The harsh words between the leaders have escalated in recent months after North Korea threatened to launch missiles toward the USA territory of Guam.
Trump had also delivered a sharp warning to North Korea in a speech at South Korea's parliament on Wednesday, telling the country: "Do not underestimate us".
"The U.S., under my administration, is completely rebuilding its military, and they're spending hundreds of billions of dollars to the newest and finest military equipment anywhere in the world, being built right now". And do not try us.The weapons you're acquiring are not making you safer, they are putting your regime in grave danger.
Trump threatened to rain "fire and fury" on North Korea and also called Kim Jong-un as "Little Rocket Man", while North Korea denounced Trump as a "mentally deranged USA dotard".