Washington (CNN) UK Foreign Secretary Boris Johnson arrived in Washington on a full court press in defense of the Iran nuclear deal, taking to the airwaves on Fox News and meeting Secretary of State Mike Pompeo to not just defend the agreement but also warn against the US pursuing a military option against Tehran.

President Donald Trump, long hostile to the Iran deal, has hinted that he will walk away from it. On Monday he tweeted that he would be announcing his decision at 2 p.m. ET on Tuesday and earlier in the day in another tweet he dismissed the 2015 pact as a "mess."

Appearing on one of the President's favorite TV programs, "Fox & Friends," Johnson asked what the US plan would be if Trump decides to opt out. Many in Washington wonder about the possibility of a military strike against Tehran -- particularly with the recent appointment of national security adviser John Bolton, a hawk on Iran.

"Are we seriously saying that we will bomb those facilities ... is that really a realistic possibility?" Johnson asked.

Johnson also warned in the interview about the consequences of scrapping the deal negotiated by the US, UK, France, Germany, China, Russia and the European Union. It offered Iran nuclear-related sanctions relief in exchange for strict curbs on its nuclear program, which would no longer apply if Iran decides to leave the deal as well.

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