Walz argues for the importance of steady U.S. leadership and a strong coalition to counter Iran's aggression, criticizing Trump's approach as ineffective and detrimental to international security. His critique, while highlighting the need for consistency in U.S. foreign policy, simplifies the multifaceted nature of Iran's nuclear ambitions and overlooks the broader international factors that influence these developments.

1. post hoc ergo propter hoc • Walz suggests a cause-and-effect relationship between Trump's withdrawal from the Iran deal and Iran's nuclear advancements without sufficient evidence that this action is what mainly led to the current state.

...we had a coalition of nations that had boxed Iran's nuclear program in, in the inability to advance it. Donald Trump pulled that program and put nothing else in its place. So Iran is closer to a nuclear weapon than they were before, because of Donald Trump's fickle leadership.

Beyond this single-cause characterization alleged by Walz, there are several other contributing causes that could explain Iran's closer proximity to developing a nuclear weapon:

1. Internal Iranian Politics: Domestic factors within Iran, such as changes in leadership, political factions gaining power, or shifts in public opinion, could drive the country's nuclear policy in a more aggressive direction. ​
2. Technological Advances: Iran's own scientific and technological advancements could have accelerated its ability to develop nuclear weapons, independent of U.S. policy changes. ​
3. Economic Factors: The impact of sanctions, both lifted and imposed, can have complex effects on Iran's economy and, by extension, its ability to fund nuclear development. Economic resilience or finding alternative funding sources could mitigate the impact of sanctions. ​
4. Regional Conflicts: The state of regional security, including conflicts in Syria, Iraq, and Yemen, might influence Iran's perceived need for a nuclear deterrent, driving its program forward. ​
5. Other Nations' Policies: The policies of other countries, including European states, Russia, and China, towards Iran can also play a significant role, either by constraining or encouraging Tehran's nuclear ambitions. ​

These factors illustrate the complexity of nuclear proliferation issues, suggesting that a multitude of variables, beyond the actions of any single nation's leadership, contribute to Iran's progress toward developing nuclear weapons. We note that Vance ignores these factors as well when he commits the same fallacy on this topic.

2. red herring • Walz introduces an irrelevant point about Trump's past behavior (crowd sizes discussion) to divert from the main issue being debated (the question of a preemptive strike on Iran).

A nearly 80 year old Donald Trump talking about crowd sizes is not what we need in this moment.

This distracts from the main issue being debated (whether to support a preemptive strike by Israel on Iran) by bringing up an irrelevant side point about Trump's age and comments about crowd sizes. It attempts to discredit Trump without directly addressing the substance of the debate topic.

This means it is also an ad hominem attack, as it is insulting Trump's age and perceived irrelevant ramblings rather than addressing the actual arguments or policies being debated about Israel and Iran, where Trump and Vance both have substantive policy positions for Walz to debate.

So, the statement commits two overlapping informal fallacies - it is both a red herring diversion from the main issue, and an ad hominem personal attack against Trump instead of addressing the substance of the topic at hand.