U.S. President Donald Trump insisted Wednesday that U.S. strikes delivered a crushing blow to Iran's nuclear program despite a preliminary American intelligence assessment suggesting that the assault inflicted only a marginal setback.

"This was a devastating attack, and it knocked them for a loop," Trump said as his administration deployed a phalanx of top officials to defend his claims that Iran's nuclear program was "completely and fully obliterated."

Iran's nuclear facilities were "badly damaged" in U.S. and Israeli strikes during the 12-day war with Israel, foreign ministry spokesperson Esmaeil Baqaei told Al Jazeera English on Wednesday.

The whipsaw chain of events involving Iran, Israel and the United States that culminated in a surprise ceasefire has raised many questions about how the Trump administration will approach the Middle East going forward.

Yet, the answer to the bottom line question — "what's next?" — remains unknowable and unpredictable. That is because President Donald Trump has essentially sidelined the traditional U.S. national security apparatus and confined advice and decision-making to a very small group of top aides operating from the White House.

Donald Trump isn't the first president to order military strikes without congressional approval. But his decision to bomb Iran comes at a uniquely volatile moment — both at home and abroad.

Overseas, the U.S. risks deeper entanglement in the Middle East if fighting erupts again between Israel and Iran. At home, Trump continues to sidestep oversight, showing little regard for checks and balances.

Iran said Tuesday it had begun efforts to rebuild residential areas and public infrastructure damaged in Israeli strikes over 12 days.

"We witnessed attacks on residential areas, as well as on scientific centres, research institutes, healthcare facilities and civilians... therefore we are facing a major task ahead in terms of reconstruction," government spokeswoman Fatemeh Mohajerani told state TV, adding that the authorities have begun to assess the extent of the damage.

U.S. President Donald Trump said Tuesday he would "probably" meet Ukrainian President Volodymyr Zelensky on the sidelines of a NATO summit in The Hague.

"Yeah probably I'll see him," Trump told reporters on Air Force One.

Russian drones, missiles and artillery killed at least 18 civilians and injured more than 100 others in Ukraine, officials said Tuesday, as Ukrainian President Volodymyr Zelenskyy sought guarantees of further Western military aid for his country's efforts to repel Russia's invasion.

Russian forces have relentlessly blasted civilian areas of Ukraine throughout the war, which is now in its fourth year. More than 12,000 Ukrainian civilians have been killed, according to the United Nations. Ukraine has also launched long-range drones against Russia, hitting residential areas.

Iran announced it had launched missiles at a major U.S. base in Qatar on Monday in retaliation for American strikes on key nuclear facilities, with explosions ringing out in Doha and projectiles seen streaking overhead.

U.S. President Donald Trump and his NATO counterparts are due to gather Tuesday for a summit that could unite the world's biggest security organization around a new defense spending pledge or widen divisions among the 32 allies.

Just a week ago, things had seemed rosy. NATO Secretary-General Mark Rutte was optimistic the European members and Canada would commit to invest at least as much of their economic growth on defense as the United States does for the first time.

Donald Trump thinks Iranians should overthrow their government if it refuses to negotiate on its nuclear program, but the US president is "still interested" in diplomacy, the White House said Monday.

"If the Iranian regime refuses to come to a peaceful diplomatic solution, which the president is still interested and engaging in, by the way, why shouldn't the Iranian people take away the power of this incredibly violent regime that has been suppressing them for decades?" Press Secretary Karoline Leavitt said on Fox News.