President Donald Trump met with his national security team in Washington for more than an hour on Tuesday to discuss the escalating Middle East conflict, according to people familiar with the matter, fueling fresh speculation that the US is on the verge of joining Israel’s attack on Iran.

Trump spoke with Israeli Prime Minister Benjamin Netanyahu following the meeting, according to a White House official, as speculation swirled around how the US president might proceed.

White House officials declined to comment or issue a statement following its conclusion.

American weapons are seen as crucial to achieving a more complete destruction of the Islamic Republic’s atomic program than anything Israel can do alone. Yet while the US is Israel’s closest defense partner and arms supplier, Trump has so far resisted calls from some political allies to join in strikes against Iran and its nuclear program.

Before gathering his advisers in the Situation Room, Trump posted a demand for Iran’s “UNCONDITIONAL SURRENDER” and warned of a possible strike against the country’s leader, Ayatollah Ali Khamenei. “We know exactly where the so-called ‘Supreme Leader’ is hiding. He is an easy target, but is safe there - We are not going to take him out (kill!), at least not for now,” Trump posted on social media.

Both Israel and Iran indicated that they planned to ratchet up the conflict, which has seen the sworn enemies trade missile salvos for five days.

The Israel Defense Forces said they had identified missiles launched from Iran toward Israel and instructed the public to take shelter in protected spaces. Explosions were heard in Tel Aviv, according to Reuters. Separately, the New York Times reported that Iran was preparing missiles for possible retaliatory strikes on US military interests in the Middle East, were Trump to proceed with an offensive campaign.

At the same time, Israel also sought to heighten pressure on Iran, indicating it would intensify a campaign of air strikes that have targeted the country’s nuclear facilities as well as military leaders and infrastructure.

Israeli Defense Minister Israel Katz said the military would attack “very significant targets in Tehran” and adding that residents should evacuate. Earlier in the day, a spokesman for the IDF said that while it was too early to assess the success of the current campaign in Iran, strikes on the country’s nuclear facilities were “deepening” every day.