The congressional defeat of a resolution of disapproval removed one of the last obstacles to the implementation of the deal, although some Republican legislators have expressed commitment to continuing their efforts to block or undermine it. Some have discussed legislative measures to expand economic sanctions despite the deal, thus effectively cancelling it. Others, such as House Speaker John Boehner, have floated the idea of a legal challenge to implementation.

Such a challenge would focus on the so-called side deals between Iran and the International Atomic Energy Agency. These agreements govern international inspections of Iran’s Parchin military base, which was considered to be central to the past military dimensions of Iran’s nuclear program. The IAEA is still working to complete a probe into the extent of Iran’s past work, in order to provide a baseline understanding of where the country stands on nuclear weapons development.

Boehner and other opponents of the nuclear deal have argued that the side deals, the text of which has not been shared with the US, are direct supplements or annexes to the Joint Comprehensive Plan of Action. If this premise is accepted, it would make those side deals subject to provisions of the Iran Nuclear Agreement Review Act which demand that all documents be provided to US legislators for review.

Regardless of whether a legal challenge could be successful on these grounds, many opponents of the deal remain adamant that the text of the side deals must be released. The International Business Times reported that several experts on nuclear proliferation had recently called for the release of this document, which the IAEA says it is obliged to keep secret out of respect for the confidential nature of all such documents.

But Olli Heinonen, a former senior IAEA official, said that there is no justification for such secrecy, especially given the importance of the subject and the apparently unusual nature of the IAEA’s approach to verification in the case of Parchin. Critics have alleged that the known details of the side deals paint a picture of inspections that are essentially controlled by the party that is subject to the inspections, thus making them highly non-credible.

While this is sure to remain a subject of debate at least through the implementation period, a legal challenge on the basis of a lack of transparency would be a longshot strategy for blocking the nuclear agreement as a whole. Additional alternatives exist and have been discussed, and Tribune reported on Friday that a number of Republican governors are pushing for a state-level approach to undermining the deal, by imposing or taking action to keep in place laws that bar states from investing their funds in businesses that have dealings with the Islamic Republic.

This strategy appears more practicable than federal alternatives, though it still appears unlikely to lead to the complete cancellation of the deal. As such, federal legislators and foreign entities who oppose the deal can likely be expected to embrace these limited sanctions as an supplementary means of mitigating the impact of the deal while also focusing on verification of Iran’s commitments now that the deal is all but certain to go into effect.

Precisely when that will occur remains uncertain. Reuters reported on Friday that the West is currently focused on October 18 as the date when the agreement will be formally adopted, but this does not necessarily translate to its immediate implementation. In fact, the Times of Israel emphasizes that there are a wide variety of steps that Iran must take first in order to demonstrate its basic commitment to the agreement before sanctions relief can go into effect.

The Obama administration would certainly like Americans to believe that it will be well prepared to monitor and verify Iran’s continuing commitment after this point. Contributing to this perception, the administration announced on Friday that it had appointed Ambassador Stephen Mull as the “lead coordinator for Iran nuclear implementation,” thus giving central authority to the process of implementation and maintenance of the terms of the deal.

But it remains to be seen whether Mull and his colleagues will take an approach to implementation that critics find sufficiently aggressive. In other words, it is unclear whether US actions will resemble the approach outlined by Adam Szubin, the acting US Treasury undersecretary for terrorism and financial intelligence, or whether they will resemble the approach described by Secretary of State John Kerry.

Iran News Update previously pointed out that Szubin had told the Senate Banking committee that the US would continue to aggressively enforce sanctions against the Iranian Revolutionary Guard Corps and other dangerous elements of the regime, whereas Kerry had given the impression that the administration would not back expansions even of non-nuclear sanctions, for fear that Iran would use it as cover for backing away from the deal.

Kerry continued to worry critics on Friday with further signs of weak commitment to enforcement. The Washington Free Beacon points out that in correspondence with concerned US legislators, the secretary of state repeatedly sidestepped requests that he report the number of American servicemen who have been killed by Iran and its proxies over the years. Texas Representative Louie Gohmert described this evasiveness as “unconscionable.”

But by simply raising this topic, the legislators did recall attention to one of the major criticisms of the deal that are not directly related to Iran’s nuclear capabilities. Critics are concerned that the estimated 100 billion dollars in new assets that Iran is set to receive upon implementation would lead to substantial increases in funding for terrorist groups that target Americans.

Kerry’s broader comments appeared to indirectly acknowledge that possibility. He responded to congressmen’s concerns about Iran’s behavior by saying that the agreement is limited to the nuclear issue and will not seriously impact the fundamental ideological differences between the two countries. Naturally, it is these ideological differences that have driven past terrorist attacks. And the persistence of those differences will fuel concerns about Iran’s possible expansion of past illicit activities.

Although unrelated to an increase in Iranian funding, one recent story already highlights the likely persistence of Iran’s aggressive behaviors and support for global terrorist groups. On Friday, the New York Times elaborated on a story that was first broken earlier in the week, regarding Iran’s release of five imprisoned Al Qaeda terrorists. The identities of those terrorists have led the intelligence community to conclude that their re-entry into the Al Qaeda organization could reenergize it at a time when it might otherwise have grown more fragile.

While Iran ostensibly arranged the release in exchange for an Iranian diplomat taken captive in Yemen, the Times points out that the five men had not been formally imprisoned in Iran but had been held under house arrest. Under these circumstances, the prisoners continued to communicate with their terrorist network outside of the country. This reflects upon the fact that Iran has been shown to have previously provided some Al Qaeda affiliates with a stable base of operations inside the country, uniquely beyond the reach of the US military.

The prospect of more such collaboration is one thing that the West will have to carefully monitor, and it is all but certain that outspoken opponents of the nuclear deal will continue to emphasize this topic as nuclear implementation moves forward in the coming months.