JERUSALEM — Hours after Vice President Joseph R. Biden Jr. vowed unyielding American support for Israel’s security here on Tuesday, Israel’s Interior Ministry announced 1,600 new housing units for Jews in East Jerusalem. Mr. Biden condemned the move as “precisely the kind of step that undermines the trust we need right now.”

Prime Minister Benjamin Netanyahu was clearly embarrassed at the move by his interior minister, Eli Yishai, leader of the right-wing Shas Party, who has made Jewish settlement in East Jerusalem one of his central causes.

A statement issued in the name of the Interior Ministry but distributed by the prime minister’s office said that the housing plan was three years in the making and that its announcement was procedural and unrelated to Mr. Biden’s visit. It added that Mr. Netanyahu had just been informed of it himself.

Mr. Netanyahu supports Jewish settlement in East Jerusalem, yet wants to get new talks with the Palestinians going and to maintain strong relations with Washington. But when he formed his coalition a year ago he joined forces with several right-wing parties, and has since found it hard to keep them in line.