ICE will begin removing 'millions' of undocumented immigrants next week, Donald Trump tweets

The president said late Monday, "They will be removed as fast as they come in."

A U.S. official, speaking on condition of anonymity, told ABC News that the deportations described by the president in Twitter aren’t imminent.

ICE does not normally unveil operational details in advance.

Separately, an administration official said Tuesday morning that enforcing final deportation orders "is a top priority."

"Countless illegal aliens not only violate our borders but then break the law all over again by skipping their court hearings and absconding from federal proceedings. These runaway aliens lodge phony asylum claims only to be no-shows at court and are ordered removed in absentia," the official told ABC News.

"There are more than 1 million illegal aliens who have been issued final deportation orders by federal judges yet remain at large in the country. These judicial removal orders were secured at great time and expense, and yet illegal aliens not only refuse to appear in court, they often obtain fraudulent identities, collect federal welfare, and illegally work in the United States. Enforcing these final judicial orders is a top priority for Immigration and Customs Enforcement — willful defiance of our laws, and the defrauding of the American People with fraudulent asylum claims, will not be tolerated,” the official said in a statement.

Less than two weeks after signing a deal with Mexico to avoid another trade war, Trump said America's neighbor to the south now is "doing a very good job of stopping people long before they get to our Southern Border."

Guatemala, Trump added, is close to signing a "Safe-Third Agreement," which means migrants fleeing from Honduras and El Salvador would be required to seek asylum there first before in the U.S.

Earlier on Monday, the State Department reported that it would freeze $185 million in aid to El Salvador, Honduras and Guatemala "until the department is satisfied the Northern Triangle countries are taking concrete actions to reduce the number of migrants."

Trump's tweets came a day before he's expected to kick off his 2020 campaign at a major event in Orlando, Florida.