Washington (CNN) The Supreme Court allowed President Donald Trump's transgender military ban to go into effect on Tuesday, dealing a blow to LGBT activists who call the ban cruel and irrational.

In an unsigned 5-4 order, the justices took no stance on the legality of the ban, first proposed in a surprise tweet by Trump in 2017, but Tuesday's action clears the way for it to take effect while lower courts hear additional arguments.

The four liberal justices objected to allowing the administration's policy banning most transgender people from serving in the military to go into effect.

The policy, first announced by the President in July 2017 via Twitter, and later officially released by then-Secretary of Defense James Mattis in 2018, blocks individuals who have been diagnosed with a condition known as gender dysphoria from serving with limited exceptions. It also specifies that individuals without the condition can serve, but only if they do so according to the sex they were assigned at birth.

In a statement released after the Supreme Court action, the Pentagon sought to clarify that its policy is not a ban on all transgender persons from the military.

"As always, we treat all transgender persons with respect and dignity. (The Department of Defense's) proposed policy is NOT a ban on service by transgender persons. It is critical that DoD be permitted to implement personnel policies that it determines are necessary to ensure the most lethal and combat effective fighting force in the world. DoD's proposed policy is based on professional military judgment and will ensure that the U.S. Armed Forces remain the most lethal and combat effective fighting force in the world," Lt. Col. Carla Gleason, a Pentagon spokesperson, told CNN.

In July 2017, Trump surprised military leaders by tweeting , "After consultation with my Generals and military experts, please be advised that the United States Government will not accept or allow Transgender individuals to serve in any capacity in the U.S. Military," Trump said. "Our military must be focused on decisive and overwhelming victory and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail."

His tweets came less than a month into the six-month delay set by Mattis to review the US military's policy on transgender service members.

The Pentagon was forced to allow transgender applicants to join the military on January 1, 2018, after a federal court ruling.

Who is affected by SCOTUS decision?

After Trump called for a ban on transgender persons serving in the military, Mattis directed Patrick Shanahan, the then-deputy secretary of defense and now-acting Secretary of Defense, and vice chairman of the Joint Chiefs of Staff Gen. Paul Selva to develop the implementation plan.

Most transgender persons are now disqualified from military service except:

Service members who have been stable for three years in their biological sex prior to joining the military -- meaning 36 months after completion of surgery and hormone treatments.

Service members diagnosed with "gender dysphoria" after joining the military can stay in the military if they don't require a change of gender and remain deployable. Gender dysphoria involves a conflict between a person's physical or assigned gender and the gender with which the person identifies, according to the American Psychiatric Association.

Service members who were diagnosed with "gender dysphoria" before the effective date of the policy can still serve and receive medical treatment.

Transgender persons without a gender dysphoria diagnosis or history can serve in their birth sex.

The Defense Department can issue waivers on a case-by-case basis.

The policy also states that transgender persons serving who require gender reassignment surgery or hormonal treatment during their service would be disqualified due to their inability to be deployed for a period longer than 12 months.

By the government's own numbers in 2016, there were approximately 8,980 Service members that identify as transgender. During the Obama administration, 937 members were diagnosed with gender dysphoria and began or completed their transition.

The Pentagon policy remains on hold at least temporarily because of an injunction from a Maryland federal judge that is technically still in place, but is expected to be paused in the next few days based on the Supreme Court's action.

A defense official tells CNN the Pentagon is not putting the transgender restrictions into place immediately, pending the resolution of the Maryland case. A Justice Department official said it will file a motion to dissolve the final injunction, and the ACLU believes the Maryland judge will follow the Supreme Court's move.

Reaction to SCOTUS decision

Shortly after the court's order, Speaker of the House Nancy Pelosi tweeted that the policy was "purpose-built to humiliate brave men & women seeking to serve their country."

"Deeply concerning that #SCOTUS is allowing his ban to proceed for now," she continued.

The court's move is a victory for the Trump administration. While government lawyers wanted the Court to take up the case, they also fought to allow the ban to go into effect while the case plays out in the lower courts.

"Today's dual rulings on the transgender ban allow the controversial policy to go into effect for now, but also allow the appeals to go forward in the lower courts," said Steve Vladeck, CNN Supreme Court analysis and professor of law at the University of Texas School of Law.

"The government had asked the Justices to take the issue up even before the appeals courts could rule. Even though the Court denied that request, the fact that the Court is allowing the policy to go into effect suggests not only that it will eventually take the case on the merits, but also that five of the Justices believe the government is likely to prevail if and when that happens," Vladeck said.

The Justice Department applauded the order, saying in a statement that the Defense Department "has the authority to create and implement personnel policies it has determined are necessary to best defend our nation."

"Due to lower courts issuing nationwide injunctions, our military had been forced to maintain a prior policy that poses a risk to military effectiveness and lethality for over a year," Kerri Kupec, a spokeswoman for the Justice Department said in a statement. "We will continue to defend in the courts the authority and ability of the Pentagon to ensure the safety and security of the American people."

Laura Durso, Vice President of the LGBT Research and Communications Project at the Cener for American Progress, called the policy "dehumanizing."

"This is the cruel centerpiece of the Trump administration's agenda to prevent the full inclusion of transgender people in public life," Durso said. "It undermines military readiness and perpetuates the fear across the transgender and allied communities that this government will not protect them, not even those who would sacrifice everything to protect our nation."