Mexico City - New U.S. Ambassador to Mexico Christopher Landau arrived in Mexico City on Friday to take up one of Washington's most important diplomatic posts, which had been vacant since Roberta Jacobson, the first woman to be the United States' envoy to Mexico, resigned and retired on May 5, 2018.

"I arrive with my hand extended. The United States wins when there is a prosperous and stable Mexico, and Mexico wins when there is a prosperous and stable United States," Landau said in brief remarks to journalists upon arriving at Mexico City's airport Friday morning. He did not take questions.

The United States and Mexico have deep cultural, familial and economic ties. The United States buys about 80% of Mexican exports, some $358 billion last year, and in the first quarter of this year Mexico was the United States' No. 1 commercial partner for the first time, ahead of Canada and China.

"Our countries are partners, neighbors and friends," Landau added. "It is that way today, and always will be."

Antonio Garza, who was U.S. ambassador to Mexico from 2002 to 2009, said Landau will be tasked with working with Mexico on the same issues that are perennially core to the relationship: trade, immigration and security.

"I think to various degrees at different times there's more urgency attached to each of those," Garza said. "With that said, I don't think that there has ever been a more critical time in terms of urgency as relates to trade, immigration and security."

Born in Madrid, Landau speaks Spanish fluently. He is a Harvard-educated lawyer who has argued nine cases before the Supreme Court and who clerked for Justices Antonin Scalia and Clarence Thomas in the early 1990s, according to a bio provided by the U.S. Embassy.