A group of 38 retired U.S. generals and admirals sent an open letter to President Donald Trump on June 12, asking him to use diplomacy rather than military force in dealing with Iran.

At the opening of the letter, they praise the nuclear deal reached with Iran in 2015. Their letter almost coincides with the second anniversary of the Joint Comprehensive Plan of Action (JCPOA), as the nuclear deal is officially known.

The retired officers also praise the compliance of all parties to the nuclear deal.

“Iran dismantled two-thirds of its centrifuges, gave up 98 percent of its stockpile of sensitive uranium, and poured concrete into the core of its heavy-water reactor. The United States

has provided proportional relief from nuclear sanctions,” the letter states.

During his presidential campaign, Trump often mocked the Obama administration’s nuclear deal, and since taking office some of his high-level officials have talked tough regarding Iran’s destabilizing moves in the Middle East.

The letter, however, does go so far as to say that “Iran’s continued ballistic missile activities, human rights violations, and support for terrorism pose a threat to the United States and our allies in the region.”

The signatories of the open letter urge the president to establish diplomatic communications channels with Iran.

“Diplomatic channels are essential not only to ensure the continued implementation of the nuclear agreement but also to resolve national security crises. We must have the ability to respond quickly and directly to de-escalate situations,” the officers write.

The generals and admirals remind the president they have led U.S. soldiers into combat and that they know what it means to put servicemen’s lives on the line. Therefore, diplomatic means should be exhausted before any risk is taken. They also ask Trump not to engage in provocations, which can get out of hand and lead to armed conflict.

But the letter also seemingly contains a contradiction. The officers urge president Trump to use “both economic leverage and negotiations to address Iran’s destabilizing behaviors.” But at the same time, they criticize U.S. Congress’s effort to put new sanctions on Iran for its ballistic missile activities.