WASHINGTON, March 14 (Reuters) - Saudi Arabia's Deputy Crown Prince Mohammed bin Salman and U.S. President Donald Trump agreed in a meeting on Tuesday that Iran represents a regional security threat, a senior adviser to the deputy crown prince said

The adviser also said the talks marked a "historical turning point" in U.S.-Saudi relations.

Saudi Arabia had viewed with unease the administration of U.S. President Barack Obama, whom they felt considered Riyadh's alliance with Washington less important than negotiating a nuclear deal with Iran in 2015. It has been encouraged by the Trump administration's hardline stance on Iran and its nuclear program.

"The meeting today restored issues to their right path and form a big change in relations between both countries in political, military, security and economic issues," the senior adviser said in a statement.

(Writing by Yara Bayoumy; Editing by Paul Tait)