The U.S. Border Patrol apprehended more than 87,000 unauthorized immigrants in the month of June, a decline compared to the steep figures reported over the last three months, according to leaked internal Department of Homeland Security data.

Why it matters: The drop enables acting DHS Secretary Kevin McAleenan to tout that the June 7 deal the U.S. struck with Mexico to stem the flow of migration is working — the kind of cover he needs to fend off attacks from prominent Trump allies.

Yes, but: Several current and former DHS officials warn Axios that border crossings tend to dip in the hotter summer months and that it's nearly impossible to tell if a policy change is effective even after a few weeks, let alone a few months.

By the numbers:

There were an average of 2,900 apprehensions per day in June.

Of the total, roughly 7,000 apprehensions were of unaccompanied minors, 52,000 were family units and 28,000 were single adults.

Although they're down from the wave of apprehensions in March through May (when apprehensions hit a high of 132,887), the numbers are higher than at any other time under the Trump and Obama administrations.

Worth noting: These preliminary figures only capture the number of apprehensions (those who cross illegally) on the southwest border through June 29. They do not include the number of inadmissibles (those who migrate through ports of entry), which is normally included in the total migration data U.S. Customs and Border Protection (CBP) releases each month. They are also subject to change, given that they're continuously updated by CBP until the final figures are published.

Also worth noting: McAleenan announced Friday that DHS was projecting a 25% drop in arrests along the border after Axios called DHS to request a comment for this story.

McAleenan announced Friday that DHS was projecting a 25% drop in arrests along the border after Axios called DHS to request a comment for this story. "It is the policy of U.S. Customs and Border Protection to not release the number of individuals who have been apprehended to deemed inadmissible [sic] for entry until between the 6th and the 8th of the following month," a DHS spokesperson told Axios. "The purpose of this policy is to ensure that the monthly numbers are reported accurately in keeping with CBP’s commitment to be accountable and transparent to the public."

Context: Earlier this month, Mexico agreed to assist the U.S. in curbing illegal migration by deploying its national guard troops throughout the country, as well expanding a new program that enables U.S. immigration officials to send Central American migrants back to Mexico while their asylum claims are being processed.

In exchange, Trump said he would not impose tariffs on billions of dollars in imports from Mexico.

But while the Trump administration continues to closely monitor these numbers, turmoil at DHS and tensions at the border have reached a fever pitch.

This week alone: McAleenan has been accused by top border officials of leaking plans for Immigration and Customs Enforcement raids targeting migrant families; acting CBP commissioner John Sanders resigned after just a few weeks in the job; and fights broke out in Congress over a bill to provide billions in additional funding for the border.

McAleenan has been accused by top border officials of leaking plans for Immigration and Customs Enforcement raids targeting migrant families; acting CBP commissioner John Sanders resigned after just a few weeks in the job; and fights broke out in Congress over a bill to provide billions in additional funding for the border. This all came amid outrage over reports of migrant children being exposed to dangerous and unsanitary living conditions, and families dying in their attempts to cross into the U.S.

Several current and former DHS officials said this week has tested their patience with McAleenan, who one official described as "a Barack Obama holdover whose philosophy, leadership style, and team he's built around him do not align with this president and this administration."