After ordering the assassination of a top Iranian commander without giving notice to congressional leaders, President Trump has told Congress to follow him on Twitter for updates on his acts of war against Iran.

These Media Posts will serve as notification to the United States Congress that should Iran strike any U.S. person or target, the United States will quickly & fully strike back, & perhaps in a disproportionate manner. Such legal notice is not required, but is given nevertheless!

— Donald J. Trump (@realDonaldTrump) January 5, 2020

Today’s dramatic tweet from the president follows another issued on January 4th, in which Trump threatened the destruction of 52 Iranian targets, including cultural sites. (The targeting of cultural sites is considered a war crime.)

....hundreds of Iranian protesters. He was already attacking our Embassy, and preparing for additional hits in other locations. Iran has been nothing but problems for many years. Let this serve as a WARNING that if Iran strikes any Americans, or American assets, we have.....

— Donald J. Trump (@realDonaldTrump) January 4, 2020

Trump has long used Twitter to harass, insult, and demean his enemies, and as president, he has used the platform to issue surprise orders, announcements, and even threats against other nations like North Korea. In 2018, Trump fired Secretary of State Rex Tillerson by tweet. More generally, federal agencies have struggled to reckon with the president’s use of Twitter during his administration, often wondering whether his mercurial pronouncements should be handled as official government policy. Nonetheless, Trump’s recent tweets are an improbable escalation of his use of the platform to incite geopolitical disorder and marginalize Congress. They may also signal illegal behaviour; according to Yale Law School processor Oona Hathaway, Trump “cannot notify Congress under the War Powers Resolution by tweet.” (Trump also later posted the same message on Facebook.)

This tweet threatens to break several laws. First, the President cannot notify Congress under the War Powers Resolution by tweet. 1/ https://t.co/tf5m8gXzCh

— Oona Hathaway (@oonahathaway) January 5, 2020

Despite now threatening war on the service, Twitter is unlikely to take action against the president’s account. In January 2018, Twitter declared that “blocking a world leader from Twitter or removing their controversial tweets would hide important information.”