The White House has grown frustrated by what it considers the Pentagon’s reluctance to provide President Donald Trump with options for a military strike against North Korea, the latest sign of a deepening split in the administration over how to confront the nuclear-armed regime of Kim Jong Un.

National Security Adviser H.R. McMaster, believes that for Trump’s warnings to North Korea to be credible, the U.S. must have well-developed military plans, officials said.

But the Pentagon, they said, is worried that the White House is moving too hastily toward military action on the Korean Peninsula that could escalate catastrophically. Giving him too many options, they said, could increase odds that he will act.

The tensions bubbled to the surface this week with the disclosure that the White House had abandoned plans to nominate a prominent Korea expert, Victor Cha, as ambassador to South Korea. Cha suggested that he was sidelined because he warned administration officials against a “preventive” military strike, which, he later wrote, could spiral “into a war that would likely kill tens if not hundreds of thousands of Americans.”

Frustration at the White House appears to be limited to senior officials. As they examine the most effective way to give credibility to Trump’s threat of “fire and fury,” officials are considering a strike to disable a missile on the launchpad or destroying North Korea’s nuclear infrastructure. They are also weighing covert ways to disable nuclear and missile programs.