Beginning today, transgender individuals can join the US military

— -- Beginning on Monday, transgender individuals will be allowed to join the U.S. military, after the Pentagon was forced to comply with a federal court ruling issued last month.

In December, the Pentagon began preparing how to let transgender individuals join the military, using court-ordered guidelines issued by former Defense Secretary Ash Carter in 2016 when he lifted the ban on transgender service members in the military.

Last summer, President Trump tweeted that transgender individuals would not be allowed in the U.S. military "in any capacity" because of the "tremendous medical costs and disruption."

A total of four lawsuits are moving through courts across the country challenging Trump’s order.

The Pentagon’s compliance on Monday only applies to allowing transgender individuals seeking to join the military. Separate court actions have temporarily halted the implementation of the ban on current transgender service members set to take place this spring.

Chief Pentagon spokesperson Dana White told ABC News on Friday that the panel of experts established by Defense Secretary James Mattis will continue and provide a recommendation to the secretary, who will then report to the president by March 23 when an implementation plan is supposed to go into effect.

New guidelines for entry

Under the guidelines effective Monday, applicants will be allowed to join the military if a medical provider certifies they have been stable without “clinically significant distress or impairment in social, occupational, or other important areas of functioning” for 18 months.

Similarly, a licensed medical provider must certify that an applicant “has completed all medical treatment associated with the applicant's gender transition, the applicant has been stable in the preferred gender for 18 months, and if presently receiving cross-sex hormone therapy post-gender transition, the individual has been stable on such hormones for 18 months.”

Applicants who have completed sex reassignment or genital reconstruction surgery must have a licensed medical provider certify that “a period of 18 months has elapsed since the date of the most recent surgery, no functional limitations or complications persist, and no additional surgeries are required.”