Four weeks into the ceasefire that has largely halted fighting in Iran, the U.S. and Iran remain locked in a standoff over the Strait of Hormuz, through which a fifth of the world’s traded oil and gas passes in peacetime.

The U.S. and Israel launched the war Saturday, targeting Iran’s leadership, missile arsenal and nuclear program while suggesting that toppling the government is a goal. But the exact aims and timelines have repeatedly shifted, signaling an open-ended conflict.

The remarks by two Iranian officials come as America has assembled its biggest deployment of aircraft and warships to the Middle East in decades. The buildup is part of President Donald Trump’s efforts to get a deal to constrain Iran’s nuclear program while the country struggles at home following nationwide protests.

Iran said the volley matched the number of bombs dropped by the United States on Iranian nuclear sites over the weekend. Iran also said it targeted the base because it was outside of populated areas.