If Israel were to annex parts of the occupied West Bank, as Prime Minister Benjamin Netanyahu promised in his re-election campaign, it would be a potentially fatal blow to the already tattered prospects for a peace agreement with side-by-side states, and could unleash a new round of violence, Palestinians warned on Monday.

But among Palestinians and in the wider Arab world, the reaction to Mr. Netanyahu’s campaign promise was largely muted, colored by a deeply skeptical view of Israeli vows and intentions.

The prime minister’s remarks changed little, many Palestinians said, because in their view the two-state peace process was dead already and Israel was headed in the direction of annexation all along. Some Palestinians said they suspect Mr. Netanyahu is playing short-term politics more than making a serious long-term political statement.

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“The truth is that annexation has been happening for the last 50 years; it just hasn’t been directly called annexation,” Fadi Quran, 31, an activist in the West Bank city of Ramallah, said on Monday.