Boeing Co. has agreed to the conditions by which it could sell aircraft spare parts to state-owned Iran Air, a move that could lead to the first sale of products by a U.S. aerospace company to the Islamic republic since 1979.

In a filing to the U.S. Securities and Exchange Commission late Wednesday, the Chicago-based commercial aircraft manufacturer said it had “entered into an agreement and engaged in related discussions with Iran Air” setting forth the general conditions by which it will sell airplane parts and other safety-related equipment.

Although Boeing hasn’t signed a final deal on specific sales to Iran, the agreement shows that major American companies are starting to benefit from a softening of relations between Iran and the West. […]