President Donald Trump severely criticized former Secretary of State John Kerry for his reported secret attempt to salvage the Iran nuclear deal, calling the former secretary of state’s actions "shadow diplomacy" that may have broken the law.

The commander in chief, in a fiery tweet posted late Monday morning, said: "The United States does not need John Kerry’s possibly illegal Shadow Diplomacy on the very badly negotiated Iran Deal. He was the one that created this MESS in the first place!"

The United States does not need John Kerry’s possibly illegal Shadow Diplomacy on the very badly negotiated Iran Deal. He was the one that created this MESS in the first place! — Donald J. Trump (@realDonaldTrump) May 7, 2018

Last Friday, The Boston Globe reported that Kerry, who was President Obama's secretary of state, met two weeks ago with a top Iranian official at the United Nations to try to use shadow diplomacy to keep the U.S. from scuttling the nuclear deal that he negotiated in 2015 under President Barack Obama.

Kerry’s powwow with Iranian Foreign Minister Javad Zarif was their second meeting in as many months, according to The Globe.

Kerry, according to the report, "has been on an aggressive, yet stealthy mission, to preserve" the nuclear deal, "using his deep lists of contacts gleaned during his time as the top U.S. diplomat to try to apply pressure on the Trump administration from the outside."

President Donald Trump has long slammed the agreement and has to decide by May 12 whether the U.S. will remain in the accord.