"This executive order sends a signal, intended or not, that America does not want Muslims coming into our country," John McCain and Lindsey Graham said. | Getty Trump: McCain and Graham 'looking to start WWIII'

President Donald Trump lashed out Sunday at Republican Sens. John McCain and Lindsey Graham for publicly second-guessing his executive order on refugees, calling them "weak on immigration" and "looking to start World War III."

The rebuke, in a pair of Sunday afternoon tweets, came after McCain (R-Ariz.) and Graham (R-S.C.) criticized Trump's executive order on immigration and refugee policy in a joint statement Sunday. They said they "fear this executive order will become a self-inflicted wound in the fight against terrorism."


Trump responded a few hours later.

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

In an appearance Sunday on CBS' "Face the Nation," McCain criticized the lack of vetting of Trump's proposal and the ensuing confusion surrounding it. Later in the day, the Arizona senator teamed up with Graham to detail their concerns, calling for a stop to restricting the return of green-card holders, interpreters and previously vetted refugees.

"This executive order sends a signal, intended or not, that America does not want Muslims coming into our country. That is why we fear this executive order may do more to help terrorist recruitment than improve our security," McCain and Graham said in the statement. Notably, however, they did not call on Trump to rescind the order and did not say they would support legislation doing so.

Trump has had a long-running feud with McCain and Graham. Sunday's escalation comes amid steady criticism from the two senators of Trump's actions concerning Russia, immigration and trade policies.

Soon after he launched his campaign in 2015, Trump criticized McCain for being captured and becoming a prisoner of war in Vietnam. Trump once gave out Graham's phone number publicly as the two battled during the GOP presidential primary.