President Trump on Thursday took aim at one of his favorite political targets – fellow Republican, Sen. John McCain – after McCain questioned the success of a military raid in Yemen that resulted in the death of a Navy SEAL.

McCain, R-Ariz., had said in a Wednesday statement that he “would not describe any operation that results in the loss of American life as a success.” White House Press Secretary Sean Spicer later fired back, saying “anyone who undermines the success of that raid owes an apology and [does] a disservice,” but didn’t mention McCain by name. Trump, however, held nothing back.

“Sen. McCain should not be talking about the success or failure of a mission to the media. Only emboldens the enemy! He’s been losing so long he doesn’t know how to win anymore, just look at the mess our country is in – bogged down in conflict all over the place,” Trump wrote in a series of morning tweets. “Our hero Ryan died on a winning mission (according to [Secretary of Defense] General Mattis), not a ‘failure.’ Time for the U.S. to get smart and start winning again!”

While the military reported taking a trove of information following the Jan. 29 nighttime raid on an Al Qaeda compound, Navy SEAL William “Ryan” Owens was killed and three other troops were wounded. U.S. forces also were forced to destroy an MV-22 Osprey aircraft after a “hard landing.”

“Senator McCain will continue to execute his oversight duties as Chairman of the Senate Armed Services Committee and support the brave men and women serving our nation in uniform,” McCain’s spokesperson said in a statement later Thursday.

Trump has frequently attacked McCain, a moderate GOP legislator who often has been critical of the president.

The war of words began when Trump said in July 2015 that McCain, who was a prisoner during the Vietnam war, was “not a war hero.” 

“He was a war hero because he was captured,” Trump said. “I like people who weren’t captured.”

Trump quickly followed that controversy by lambasting McCain for problems at the VA. In October 2016, as Trump was being pilloried after a decade-old audio surfaced that featured Trump making crude remarks, Trump hit McCain for not supporting him.

“The very foul mouthed Sen. John McCain begged for my support during his primary (I gave, he won), then dropped me over locker room remarks!” Trump tweeted Oct. 11.

When Trump’s executive order temporarily restricting immigration from seven mostly Muslim countries drew a rebuke from McCain and Sen. Lindsey Graham, Trump again took to Twitter.

“The joint statement of former presidential candidates John McCain & Lindsey Graham is wrong – they are sadly weak on immigration,” he wrote. “The two Senators should focus their energies on ISIS, illegal immigration and border security instead of always looking to start World War III.”