The Department of Homeland Security on Monday defended the Trump administration's zero tolerance border policy and said opponents of that policy are purposefully mischaracterizing it by saying family separations at the border are becoming a crisis.

"In recent days, we have seen reporters, Members of Congress, and other groups mislead the public on the Department of Homeland Security’s (DHS) zero-tolerance policy," the memo stated. "Repeating intentionally untrue and unsubstantiated statements about DHS agents, officers, and procedures is irresponsible and deeply disrespectful to the men and women who risk their lives every day to secure our border and enforce our laws."

[Kirstjen Nielsen: No plan to stop separating families at the border despite public outrage]

The memo comes as Democrats continue to argue that the Trump administration created the policy of separating children from their parents or guardians as they try to prosecute the adults for illegal immigration. But DHS said that argument isn't true.

"DHS does not have a blanket policy of separating families at the border. However, DHS does have a responsibility to protect all minors in our custody. This means DHS will separate adults and minors under certain circumstances," the department stated. "These circumstances include: 1) when DHS is unable to determine the familial relationship, 2) when DHS determines that a child may be at risk with the parent or legal guardian, or 3) when the parent or legal guardian is referred for criminal prosecution."

Another "myth" DHS tried to dismiss was that it works against keeping families together through the immigration adjudication and removal process. It pointed to a court decision as the reason for current procedure.

"Court decisions interpreting the Flores Settlement Agreement (FSA), which has been in existence for over 20 years but was significantly broadened in 2015, limits the government’s ability to detain family units. Pursuant to these court decisions, minors detained as part of a family unit cannot be detained in unlicensed facilities for longer than a presumptively reasonable period of 20 days, at which point, minors must be released or transferred to a licensed facility," DHS stated. "Because most jurisdictions do not offer licensure for family residential centers, DHS can rarely detain a family for longer than 20 days."

It also maintained its housing for minors is not comparable to "inhumane fenced cages" or an "ice box."

"DHS and HHS utilize short-term facilities in order to process and temporarily hold migrants that have been apprehended. These short-term facilities do not employ the use of ‘cages’ to house minors. Certain facilities make use of barriers in order to separate minors of different genders and age groups – for the safety of those who are being held. Additionally, CBP facilities have adequate temperature control and ventilation," it stated.

Only people who claim to be part of a family unit who are apprehended while trying to enter the U.S. in between checkpoints will be arrested for illegal entry.

Those who show up at a port of entry and claim asylum may have to deal with long lines, but will be kept with their families as they go through immigration proceedings, which includes an interview with a U.S. Citizenship and Immigration Services officer and hearing before an immigration judge.

DHS denied reports that it is turning away asylum seekers at ports.

"As the number of arriving aliens determined to be inadmissible at ports of entry continues to rise, CBP must prioritize its limited resources to ensure its primary mission is being executed," the department stated. "Depending on port circumstances at the time of arrival, CBP officials will allocate the necessary resources to its primary mission and operate appropriate access controls and queue management procedures for those arriving aliens without proper travel documents."

[Also read: White House: Democrats are turning family separation into an 'emotional issue' for midterm advantage]