WASHINGTON (Reuters) - President-elect Donald Trump’s national security transition has been more chaotic than others in recent memory, with important positions unfilled and many of his people less able, or willing, to engage on substance, U.S. officials said.

Principal Deputy Director of National Intelligence Stephanie O'Sullivan answers questions during the Senate Intelligence Committee hearing on the House-passed Foreign Intelligence Surveillance Act reform bill while on Capitol Hill in Washington, June 5, 2014. REUTERS/Larry Downing

The uncertainties surrounding Trump’s personnel, policies, and rise to power have rattled many of America’s allies, including Japan, Germany and Britain, at a time when China is more assertive, Russia more aggressive, terrorism more diffuse, the Middle East still unstable and North Korea nuclear-armed and unpredictable, said U.S. and foreign diplomats.

Disruption and uncertainty can provide strategic advantages, Mark Lagon and Ross Harrison of Georgetown University wrote in Foreign Policy magazine. “But what is seriously in doubt is whether Trump’s disruption will be strategic or beneficial to U.S. foreign policy interests. Even before getting elected, he acted like a missile without a guidance system.”

Top Trump officials, however, described the transition as having gone smoothly, including on national security.

Republican Trump’s camp announced on Thursday it had asked more than 50 of Democrat Obama’s appointees to stay on.

However, at least three officials, a senior intelligence officer and two diplomats whose names are on a list of “requested political holdovers,” will depart.

Principal Deputy Director of National Intelligence Stephanie O’Sullivan, Under Secretary of State Catherine Novelli and Assistant Secretary of State Toria Nuland appear on a Jan. 17 partial list of people the transition wanted to remain after Trump’s inauguration on Friday.

The two diplomats have told colleagues they are going, and O’Sullivan is keeping her long-standing plans to retire. A U.S. official said that Nuland was never asked by the transition to stay on and was unaware of her name appearing on such a list.

The State Department declined comment. The Trump transition and the Office of the Director of National Intelligence did not immediately respond to a request for comment.

It is not clearly whether the uncertainties extend to other parts of the government, but another senior official at a national security agency said Trump’s effort was “much slower” than the 2001 Bill Clinton-to-George W. Bush or the 2009 Bush-to-Barack Obama handovers.

“Personnel appointments were far more advanced in both those cases,” said the official, who spoke on condition he not be identified. “In both cases, advance teams were working on substance.”

During the 2008-2009 transition, the official said, incoming and outgoing officials had worked together on issues “in a very harmonious fashion.”

“None of that is the case in this transition,” he added. He said that he had expected to have met by now with his likely replacement or others on the transition, but had not. “It’s not just me. Everybody’s experience is like mine.”

‘REAMS OF BRIEFINGS’

Speaking to reporters on Thursday, Vice President-elect Michael Pence said Trump’s transition was being completed ahead of schedule and under budget. “Our job is to be ready on day one. The American people can be confident that we will be.”

Trump spokesman Sean Spicer also told reporters that contact between the incoming and outgoing National Security Council staffs had been “tremendous.”

“We’ve had reams of briefings,” he said. “That is one area where frankly they have been very, very aggressive and robust with both meeting with their counterparts and ensuring that the team is ready to go day one.”Trump’s team did not respond to requests for further comment.

Three State Department officials, though, called the transition there “a mess,” and said that until recently the Trump team had little contact with department officials and read few if any of their briefing books.

That has left many career officials with misgivings about the incoming administration and the possibility that many foreign policy and national security veterans may be swept out.

A dozen serving officials at four intelligence agencies said they are troubled by Trump’s apparent disdain for their work; by his designated national security advisor Michael Flynn’s perceived bent for conspiracy theories and hostility toward some of his former colleagues; and by what some say is the incoming president’s disinterest in the briefings he has received.

Two officials with knowledge of those briefings said Trump’s attention has wandered, he has asked few questions, has read few if any of the briefing books he’s been given – including the one on Russian hacking of the 2016 election - and has requested few topical sessions, one of which was on North Korea.

Secretary of State John Kerry and his nominated replacement, Rex Tillerson, were to meet on Thursday, but their schedules did not mesh, State Department spokesman John Kirby told reporters.

One Obama official, who has dealt with the Trump transition team at the State Department and spoke on condition of anonymity, said it appeared ‘totally disconnected’ from Trump’s top echelon of advisers and from Tillerson.

Tillerson’s nomination is not expected to get a Senate Foreign Relations Committee vote before Monday at the earliest.