Senators are set to meet with top national security officials Thursday as many question President Donald Trump's decision to bomb three Iranian nuclear sites — and whether those strikes were ultimately successful.

The classified briefing, which was originally scheduled for Tuesday and was delayed, also comes as the Senate is expected to vote this week on a resolution that would require congressional approval if Trump decides to strike Iran again. Democrats, and some Republicans, have said that the White House overstepped its authority when it failed to seek the advice of Congress and they want to know more about the intelligence that Trump relied on when he authorized the attacks.

The heads of the European Union's 27 member nations will meet Thursday in Brussels to discuss tougher sanctions on Russia, ways to prevent painful new U.S. tariffs, and how to make their voices heard in the Middle East conflicts.

Most of the leaders will arrive from a brief but intense NATO summit where they pledged a big boost in defense spending, and papered over some of their differences with U.S. President Donald Trump.

Israel and Iran seemed to honor the fragile ceasefire between them for a second day Wednesday and U.S. President Donald Trump asserted that American and Iranian officials will talk next week, giving rise to cautious hope for longer-term peace.

Trump, who helped negotiate the ceasefire that took hold Tuesday on the 12th day of the war, told reporters at a NATO summit that he was not particularly interested in restarting negotiations with Iran, insisting that U.S. strikes had destroyed its nuclear program. Earlier in the day, an Iranian official questioned whether the United States could be trusted after its weekend attack.

Iran on Wednesday hanged three men convicted of spying for Israel after what activists decried as an unfair trial, bringing to six the number of people executed on such charges since the start of the war between the Islamic republic and Israel.

Iran on Wednesday branded NATO Secretary General Mark Rutte's gushing note to President Donald Trump on U.S. strikes targeting key nuclear sites as "disgraceful, despicable and irresponsible".

Ukrainian President Volodymyr Zelensky said Wednesday he had discussed a ceasefire in Ukraine with U.S. leader Donald Trump on the sidelines of NATO's summit in The Hague.

President Donald Trump on Wednesday hailed a NATO pledge to boost defense spending to five percent of gross domestic product annually as a "monumental" win for his country.

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.