President Trump suddenly faces two global crises in North Korea and Iran — via Iraq — both with the real possibility of U.S. military action, if not war.

Why it matters: Trump has benefited from relative peace abroad and prosperity at home. But these twin challenges will truly test his diplomatic mix of bluster and buddying up to bad guys on the world stage.

Iran-backed militiamen attacked the U.S. embassy in Baghdad, Iraq, Wednesday for the second day in a row. Marines guarding the embassy fired tear gas after the protesters lit a fire on the roof of the reception area, per AP.

On New Year's Eve, Trump ordered the deployment of 750 soldiers from the Army’s 82nd Airborne Division from Fort Bragg, N.C., to the Middle East. 3,000 more prepared for possible deployment in the next several days.

The protestors at the embassy later withdrew after orders from the militias, saying their message had been heard and that would now try to remove U.S. troops from Iraq by taking action in the country’s parliament.

"Little Rocket Man," North Korea's Kim Jong-un, is threatening to resume nuclear-missile testing, and said he'll soon introduce "a new strategic weapon" as the momentum of the past few years has stalled.

He declared in a New Year's speech that there "will never be denuclearization on the Korean peninsula" unless the U.S. drops its "hostile" policies, according to state media.

Don't forget: Russia said last week that it had deployed a hypersonic nuclear missile that President Vladimir Putin claims is in a class of its own, "fueling concerns of a new arms race with the U.S.," per Bloomberg.

Go deeper: Trump's New Year's crisis