The United States said Monday that West Bank settlers' killing of a 19-year-old Palestinian was "terror," sharpening its tone on far-right Israeli violence.

The State Department's bureau in charge of the Middle East in a weekend post on Twitter, which has been rebranded X, strongly condemned the "terror attack by Israeli extremist settlers."

State Department spokesman Matthew Miller made clear Monday that the word choice was not an accident.

"The thinking is that it was a terror attack, and we are concerned about it, and that's why we called it that," he told reporters.

"We have also been clear that accountability and justice should be pursued with equal rigor in all cases of violent extremism, whoever the perpetrators are," he said.

He noted that Israel has made arrests, which he called "appropriate action."

Qusai Jamal Maatan was shot dead in Burqah, east of Ramallah, on Friday as armed settlers clashed with villagers.

Israeli media said that one of two suspects was a former aide to a lawmaker from the far-right Jewish Power party, whose leader Itamar Ben-Gvir is public security minister.

The United Nations has warned of a dramatic spike in violence since Israel's most right-wing government in history took office late last year in a coalition led by Prime Minister Benjamin Netanyahu.

US President Joe Biden's administration has repeatedly criticized actions and statements from the coalition government while stopping short of countermeasures that could trigger public spats with Netanyahu, who is popular with the rival Republican Party.

The United States under president George W. Bush waged a global "war on terrorism" following the September 11, 2001 attacks by Islamist extremists.

His successor Barack Obama was more sparing in the use of the word "terrorism," preferring the less loaded "violent extremism."