Story highlights Veterans Sen. Tammy Duckworth and Rep. Ted Lieu also denounced the decision

Sen. John McCain, the chair of the armed services committee, called it 'unclear'

Washington (CNN) Sen. John McCain objected to the Trump administration's decision to reinstate the US ban on transgender people serving in the military Wednesday, saying an announcement by President Donald Trump on Twitter was "unclear."

"The statement was unclear. The Department of Defense has already decided to allow currently-serving transgender individuals to stay in the military, and many are serving honorably today. Any American who meets current medical and readiness standards should be allowed to continue serving," the Arizona Republican said in a statement. "There is no reason to force service members who are able to fight, train, and deploy to leave the military -- regardless of their gender identity. We should all be guided by the principle that any American who wants to serve our country and is able to meet the standards should have the opportunity to do so -- and should be treated as the patriots they are."

McCain, the chairman of the Senate armed services committee, added that no decision is appropriate until the study is complete and reviewed by the secretary of defense, military leadership and Congress.

McCain's criticism comes one day after he dramatically returned to Washington following surgery for brain cancer. After voting to advance consideration of Republican health care plans, he delivered a well-received speech on the Senate floor calling for more bipartisanship in the chamber.

The Arizona Republican was joined by lawmakers on both sides of the aisle who pushed back against Trump's decision to reinstate the ban barring transgender individuals from serving "in any capacity" in the US armed forces.