WASHINGTON — Washington’s European allies are urging the Donald Trump administration to stick with the Iran nuclear deal, while offering to collaborate on other ways to address outstanding issues such as Tehran’s support for militant proxy groups in the region and its ballistic missile program.

The conversations between Washington and its close European allies come ahead of a Sept. 14 deadline for the US administration to issue a waiver suspending nuclear-related oil sanctions as required under the Joint Comprehensive Plan of Action (JCPOA), and ahead of the next quarterly deadline, on Oct. 15, for the Trump administration to certify to Congress whether Iran is complying with the accord. They also come as the Trump administration is finalizing an interagency review of its broader policy toward Iran, of which the JCPOA is just one aspect.

Trump has reiterated to aides just in the past few days that he wants to get tougher on Iran, but it is not clear how, said a US official, speaking not for attribution. A nearly completed US interagency review of broader policy on Iran recommends sticking with the JCPOA, but to find ways to be tough on Iran. The challenge is how.

The US official said he thought that the administration is leaning toward certifying Iran’s compliance with the JCPOA to Congress next month, but he cautioned that could change. And Trump’s former White House strategist Steve Bannon, a critic of the deal, said over the weekend that he would not count on Trump certifying.