Joint Base Andrews, Maryland - US Secretary of State Marco Rubio on Wednesday warned Israel against annexing the West Bank, saying steps taken by parliament and settler violence threatened a Gaza ceasefire deal.

Israeli lawmakers voted Wednesday to advance two bills on annexing the occupied West Bank, barely a week after President Donald Trump pushed through a deal aimed at ending a two-year Israeli assault on the Gaza Strip.

"I think the president's made clear that's not something we can be supportive of right now," Rubio said of annexation as he boarded his plane for a visit to Israel.

Annexation moves are "threatening for the peace deal," he told reporters.

"They're a democracy, they're going to have their votes, and people are going to take these positions," he said.

"But at this time, it's something that we...think might be counterproductive," he added.

Asked about increased violence by extremist Israeli settlers against Palestinians in the West Bank, Rubio said: "We're concerned about anything that threatens to destabilize what we've worked on."

But Rubio – the latest high-ranking US visitor to Israel following Vice President JD Vance – voiced optimism overall for preserving the ceasefire deal.

"Every day there'll be threats to it, but I actually think we're ahead of schedule in terms of bringing it together, and the fact that we made it through this weekend is a good sign," Rubio said.

The US is the primary military and diplomatic supporter of Israel, and Rubio until recently had steered clear of criticizing annexation moves championed by Prime Minister Benjamin Netanyahu's far-right allies.

But a number of Arab and Islamic states, which the US is courting to provide troops and money for a stabilization force in Gaza, have warned that annexation of the West Bank was a red line.