Why do you think justification is required?
Suleimani's assassination was committed when he was a guest of the Iraqi Prime Minister.
He was allegedly mediating back channel communications between Iran and Saudi Arabia designed the help Trump live up to his promise to end US wars in the Middle East; do you think Trump lied about that too?
The 40 Year Cold War With Iran - CounterPunch.org
"Donald Trump has tried to convince the American electorate that he wants to end America’s endless wars in the Middle East by withdrawing troops from Afghanistan, Syria, and Iraq.
"Even before the recent escalation of tensions with Iran, however, Trump
sent an additional 14,000 troops to the Middle East.
"After the latest drone strikes, he has announced the dispatch
of 3,000 more.
"When is a surge not a surge?
"When Donald Trump orders one.
"This latest assassination reveals Trump’s real intentions.
"He is not interested in ending America’s endless wars.
"Rather, he is rushing to add one more to the list.
"The current crisis might be averted, but the longer war with Iran continues."