The joint chiefs of staff of South Korea said in a statement in Seoul that its naval vessels will participate in the drills.
The three carriers will be likely together in the drills around Monday.
Xi urged South Korea to take a "responsible attitude on THAAD that stands the test of history", adding that it would be "new beginnings and a good start".
A total of seven South Korean navy vessels, including Aegis-equipped warships, will participate in the drill, the statement said, to accompany 14 US naval warships.
During the joint drill, the two countries will practice air operation and artillery strikes, as well as aircraft carrier escorts to test their ability to jointly carry out operations.
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The objective of the optional composition scheme is to bring simplicity and reduce the compliance cost for the small businesses. He added that the impact of these changes would be positively felt in the next few months.
The US administration thinks China's economic leverage over North Korea is the key to strong-arming Pyongyang into halting its nuclear weapons and missile programmes.
It's the first time since a 2007 exercise near Guam that three U.S. carrier strike groups are operating together in the Western Pacific, according to the U.S. Navy's 7th Fleet. U.S. Pacific Fleet Commander Admiral Scott Swift described the training as a "rare opportunity".
Show of force coincides with US President Trump's visit to AsiaThis weekend, three American aircraft carriers will be carrying out joint exercises in the waters around the Korean Peninsula. They will successively enter the exercise area in global waters east of the Korean Peninsula over the weekend, and at one point around Monday will operate together.
Yonhap said the three aircraft carriers will enter the KTO one by one as the strike groups sail with a certain distance from each other.
In his speech before South Korea's National Assembly Wednesday, Trump told North Korea: "Do not underestimate us, and do not try us".
South Korea and the United States have repeatedly said THAAD only serves to defend against the growing missile threat from North Korea.