WASHINGTON — US President Donald Trump said Iran has lost most of its missile and drone production capacity and now retains only about 21% to 22% of its missile stockpile following months of conflict.In excerpts released Friday from an interview with NBC News scheduled to air Sunday, Trump said Iranian missile manufacturing facilities, drone factories and launch sites had been largely destroyed.“Most of the drone factories have been knocked out, most of the launching pads have been knocked out, and most of the missile manufacturing areas have been knocked out,” Trump said.“They still have capacity. They have some missiles, they have some drones,” he added.“I would say percentage-wise, maybe 21%-22% of their missiles. It's a lot of missiles, but it's not what it was when we first attacked.”Asked why Iran had not yet agreed to a permanent deal to end the conflict despite what he described as pressure on Tehran, Trump said Iranian leaders were reluctant to accept terms they had previously rejected.“They're proud, and there are things they never thought they'd be doing that they're going to have to do. They've got no choice, and it takes a little while,” he said.When questioned about withdrawing from the original Iran nuclear agreement during his first term and whether a better deal could have been reached sooner, Trump said negotiations of that scale require time.“It takes years to do these things. These people have been fighting for 47 years,” he said.The United States and Iran continue to exchange proposals through Pakistani-mediated talks aimed at reaching a broader agreement to permanently end the conflict that began on Feb. 28.