KABUL, Afghanistan — The Taliban announced the beginning of their spring offensive on Friday, even as the United Nations lifted travel bans on 11 of their senior leaders to facilitate peace talks with the United States.

The announcements were a sign that though the peace talks are gaining momentum, with an Afghan delegation expected to meet with insurgents soon, fighting is likely to intensify all over the country.

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Violence has gotten worse in recent weeks as the weather has warmed across Afghanistan, with each side killing dozens of the other’s forces every day. Last month, the government pre-empted the Taliban by announcing its own spring military offensive, amid Afghan leaders’ frustration over having been left out of the talks aimed at setting terms for an American troop withdrawal.

Two senior Western officials said the government’s early announcement appeared to have been a mistake, with lower-ranking officials having released it without the leadership’s approval. President Ashraf Ghani signed off on the security plan nearly two weeks after it was announced.