The Obama administration isn't claiming "mission accomplished" but it may be as close as the White House can get.

The Border Patrol announced today that the unaccompanied minors crisis has all but ended, as the rise in children crossing the Southwest border has stopped.

"It's premature to say it's over but significant progress [has been] made" in stopping unaccompanied minors, Department of Homeland Security Deputy Secretary Alejandro Mayorkas said today at the National Press Club.

"It is now five months later, and the number of children arriving and apprehended at our border is dramatically lower than it was five months ago," Mayorkas said, citing factors both in officials' control and outside factors.

"Historically, for example, the month of August sees a precipitous drop in the number of migrants reaching the Southwest border by virtue of the season and time of year, by the heat and the like," he said. "That very well may play a factor in what we've seen."

Between Oct. 1 and the end of August, the Southwest border saw more than 66,000 children apprehended, mostly coming from Central American countries. That represented an 88 percent increase over the same period a year earlier.

More than 10,000 children were apprehended in both May and June, while July saw just more than 5,500, and August around 3,100.

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"It would be premature, at best, to declare victory and to say that the problem is behind us. Because we don't know," Mayorkas said. "What we have achieved is tremendous progress and if, indeed, we begin to observe an uptick in the number of unaccompanied children … we are prepared to address that uptick very swiftly."

The White House began making its case for executive action on immigration reform Monday night by circulating a blog written by the commissioner of the Border Patrol - Gil Kerlikoski.

President Obama has admitted he lost public support for unilateral reform when thousands of unaccompanied minors and mothers with children began crossing the border in never-before-seen numbers this spring.

In advance of promised presidential action in November, the Border Patrol announced that the Mexican frontier is "more secure that it has been in decades," and that " decisive action" has brought the influx of Central American children under control.

For the second month in a row - August, following July - the number of unaccompanied minors has declined.

"Victory is accomplished when those cities and towns that suffer violence and suffer the vicissitude of life no longer do, such that children do not have to flee seeking relief and refuge elsewhere," Mayorkas said. "That, I think, would be victory. And that is something that involves much more than what we are speaking about this morning."

During the news conference, Mayorkas also addressed concern that the terrorist group ISIS has been planning to enter the United States through the Southwest border.

"There is no credible information that there is an active plot to traverse the Southwest border now," Mayorkas said. "That being said, we, as a Department of Homeland Security, have the obligation to be, and are very much, vigilant in terms of our nation's security - whether that be by land, by sea or by air."