A bipartisan group of national security leaders on Sunday warned that the Trump administration's strategy toward Iran could lead to a larger conflict, as the president plans to attend the upcoming United Nations (U.N.) General Assembly.

In a statement released by the group National Coalition To Prevent An Iranian Nuclear Weapon, more than 50 prominent foreign policy figures said the administration's pressure campaign against Tehran "has left Iran the option of either capitulation or war."

“The Trump Administration’s Iran strategy is to assert maximum economic, political and military pressure to change Iran’s behavior and threaten, if not cause, collapse of the regime. But since it has not undertaken diplomatic engagement on any of its twelve demands on Iran, the Administration has left Iran the option of either capitulation or war,” the leaders wrote.

The signatories of the letter, which include former Secretary of State Madeleine Albright, former Director of National Intelligence James Clapper James Robert ClapperOn China, Biden is no Nixon — and no Trump The Hill's 12:30 Report - Speculation over Biden's running mate announcement Trump slams former intelligence officials to explain 'reluctance to embrace' agencies MORE and former Sens. Richard Lugar (R-Ind.) and Carl Levin Carl Milton LevinMichigan to pay 0M to victims of Flint water crisis Unintended consequences of killing the filibuster Inspector general independence must be a bipartisan priority in 2020 MORE (D-Mich.), argued President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE's decision to pull out of the Iran nuclear deal in May has made achieving his administration's goals more difficult.

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"The Administration’s suggested policy of regime change in Iran reflects wishful thinking and a flawed interpretation of intelligence about Iran’s vulnerability," the signatories wrote. "The 2003 U.S. invasion of Iraq remains a striking reminder of our inability to estimate accurately the long-term impact of U.S. actions."

The letter, however, is not entirely critical of the administration's strategy and vouches for the importance of ensuring an Iran free of nuclear weapons, something Trump and his allies have long called for.

The letter comes shortly after Iranian President Hassan Rouhani blamed the U.S. for supporting militants who attacked a military parade in the country, killing at least 29 people. Iran has accused Saudi Arabia, a close U.S. ally in the region, of orchestrating the attack.

On Sunday, U.S. Ambassador to the U.N. Nikki Haley Nimrata (Nikki) Haley'The soul' versus 'law and order' Author Ryan Girdusky: RNC worked best when highlighting 'regular people' as opposed to 'standard Republicans' GOP lobbyists pleasantly surprised by Republican convention MORE dismissed the accusations, saying the U.S. was not to blame and that the Trump administration had no interest in regime change in Iran.

The letter also comes ahead of Trump's appearance at the U.N., where he is set to chair a Security Council meeting on the nonproliferation of weapons of mass destruction. Observers expect him to use the opportunity to attack Iran.

Trump entered the White House promising to take a tougher approach to Tehran than his predecessor, former President Obama. Since then, he has added John Bolton, a noted Iran hawk, to his Cabinet, and reimposed sanctions on Tehran as part of the withdrawal from the nuclear deal in May.

He also raised eyebrows earlier this summer when he warned Rouhani in an all-caps tweet that Iran could suffer unspecified consequences.