WASHINGTON – More than a month after he became America's top diplomat, Rex Tillerson is like no other modern secretary of state: He's largely invisible.

He has given no media interviews and has not held a single news conference. He has made two brief trips abroad — and was overshadowed both times by other Cabinet officials. His news releases are chiefly independence day greetings to other nations.

The White House blocked him from appointing his choice for a deputy, so he still has none. Dozens of assistant secretary positions, the diplomats who head bureaus for specific regions and issues, also are unfilled.

Tillerson only occasionally meets President Donald Trump or his staff at the White House, and he has been conspicuously absent from key meetings and conversations with foreign leaders.

Foreign governments that previously studied the near-daily State Department briefings for guidance on U.S. policy on matters large and small have little to go on. The last public briefing was on Jan. 19, the day before Trump took office; they are set to resume on March 6, but on an irregular schedule.

Fox News anchor Heather Nauert has been hired as spokeswoman for the department, according to two people familiar with the matter.

The State Department is said to be facing deep budget cuts that could significantly curtail Tillerson's ability to conduct the global diplomacy that is the backbone of U.S. foreign policy.

It's not clear whether Tillerson's under-the-radar style reflects his personality, or if he is following a script from a White House that has taken control of foreign policy in the Middle East and with Mexico, and has stressed a robust military buildup over diplomacy and foreign aid.

Previous secretaries of State — John Kerry, Hillary Clinton, Condoleezza Rice, Colin Powell, among others — were global celebrities.

It might be argued how much power each ultimately wielded, but all were highly visible, frequently seen at his or her president's side or in top-level encounters with world leaders.

Aaron David Miller, a former U.S. diplomat who served under six secretaries of state, described a marginalized Tillerson heading an "incredibly shrinking State Department."

Miller said Tillerson appears to be competing for influence at the White House with Jared Kushner, Trump's son-in-law, and Steve Bannon, the president's chief strategist.

"A way has to be found to empower Tillerson," Miller said. "Without that, it takes five seconds for allies or adversaries to understand that the secretary of state does not have a whole lot of weight."

Other foreign policy experts worry that the administration has been so slow to fill scores of policy and operational positions in the department, leaving acting appointees in charge.

"Some are very good, but it still means none have any authority," said Henri Barkey, a former State Department official who now heads the Middle East program at the nonpartisan Wilson Center think tank.

"There is no policy out there, and it is not clear Tillerson knows what he's supposed to do," he added.

In Washington, foreign diplomats and organizations that routinely work with the State Department say it appears rudderless.

"There is no one under him," said a Western diplomat who asked not to be identified because the diplomat's embassy must deal with the State Department. Visiting delegations "have meetings but find everyone in listening mode."

"Clearly no one below Tillerson is making any decisions, and people are trying to figure out what he wants," said the representative of an advocacy group who also asked not to be identified because the group is partly funded by the State Department.

As a CEO of the global energy conglomerate Exxon Mobil before he joined the administration, Tillerson preferred flying to global capitals with a small entourage, swooping in to make deals. He answered only to a board of directors and shareholders.

With the FBI and several congressional committees investigating whether the Trump team had improper contacts with Russian authorities, perhaps it's not surprising that Tillerson — who was close to Russian President Vladimir Putin several years ago — has kept his head down.

But his semi-disappearing act after decades of high-profile, globe-trotting secretaries of state has far-reaching implications for America's position in the world.

Since taking office, Trump has alarmed allies by deriding the role of international institutions and trade pacts, squabbling with leaders of Mexico and Australia, challenging decades of policy with China and announcing a neo-isolationist "America First" policy toward the rest of the world.

"My job is not to represent the world," Trump said Tuesday night in his first speech to Congress. "My job is to represent the United States of America."

Tillerson felt compelled to weigh in the next day, issuing a statement that seemed aimed at salvaging his role as well as America's use of soft power and military might, around the world.

The State Department "will continue to engage to advance U.S. interests in the world in cooperation with our partners and allies," Tillerson said. "American foreign policy must promote our core values of freedom, democracy, and stability."