WASHINGTON (NYTIMES) - US Secretary of State Antony Blinken has kicked off his first month in the job with a blaze of diplomacy.

As part of his effort to re-energise American alliances frayed by the Trump years, Mr Blinken has spoken with dozens of his counterparts around the world and joined gatherings of Asian and European leaders - all without ever leaving his seventh-floor office at the State Department.

As the world struggles to get the coronavirus pandemic under control, most diplomatic travel remains postponed. In ordinary times, Mr Blinken would have hosted a stream of visitors and logged thousands of air miles by now; instead, he has relied on the telephone and video screens, much like Zoom-dependent workers everywhere.

"It's a good thing we're on the family plan here at the State Department, otherwise I'd be broke," Mr Blinken told NPR this month.

Behind the jokes, however, there is frustration. Mr Blinken and President Joe Biden say the United States faces a herculean challenge in restoring bonds with key allies, re-establishing American leadership against rivals like China and Russia, and confronting threats such as climate change and a nuclear Iran.

Although Mr Blinken has been vaccinated against the coronavirus, State Department officials say they are being cautious about his foreign travel, which involves an entourage of aides, security personnel, support staff and journalists, many of whom would be at risk of contracting or spreading the virus.

Mr Blinken currently has no travel planned, and a senior administration official said he might not take to the air before April - though even that timeline is uncertain.

That, former government officials and diplomacy experts say, is an undeniable handicap, especially at a moment of such flux in the world.

Plenty of business can be done through phone calls and video meetings. But diplomats say proximity breeds a familiarity that cannot be replicated, fuelled by body language, eye contact and handshakes, shared meals, cultural events, exchanged gifts and the serendipity of hallway encounters, outdoor walks and other moments away from neurotic, agenda-clutching aides.

Mr Blinken was, for instance, unable to make an in-person appearance at the annual Munich Security Conference, a forum staged virtually last week for American and European elites to speak, schmooze, strategise and affirm trans-Atlantic bonds. On Monday (Feb 22), he held a video call with European Union foreign affairs ministers.

In ordinary times, those events might have been "part of a sweeping Europe trip to include the Munich Security Conference and a trip to NATO," said Cathryn Clüver Ashbrook, the executive director of The Future of Diplomacy Project at Harvard University's Belfer Center for Science and International Affairs.

Ms Clüver Ashbrook said that missing out on the events in person "is a lost opportunity at this moment of reinvigoration for the trans-Atlantic relationship in particular," not least because of the many side meetings that occur around the Munich event.

"You think of all the pictures from the summits, where the leaders are leaning over one another," she said. "That's where the actual details are ironed out."

The current stasis is notable in comparison with Mr Blinken's predecessor, Secretary of State Mike Pompeo, who, along with other senior State Department and White House officials during the Trump administration, slowed the pace of their travel during the pandemic.

But that travel agenda was part of an overall business-as-usual ethos towards the virus criticised by health experts, and it by no means halted travel, which came with predictable results. After returning from meetings with officials in London and Paris last fall, for instance, Mr Pompeo's director of policy planning tested positive for the coronavirus, aggravating allies over their potential exposure.

It is not just Mr Blinken who is grounded, but his wider team. (Mr Biden also has no plans to travel abroad soon, the White House says.) The climate envoy John Kerry, a former secretary of state known for his boundless appetite for foreign travel, has not yet left the country and has no specific plans to do so. The same goes for Mr Blinken's Iran envoy, Robert Malley, who otherwise would likely be shuttling between Europe and the Middle East to confer with allies.

By contrast, President Barack Obama's special envoys, including ones for the Middle East, Afghanistan and Pakistan, hit the road almost immediately in 2009.

One exception is the State Department's envoy for war-ravaged Yemen, Timothy A. Lenderking, who departed on Monday for his second trip to Saudi Arabia in pursuit of a Yemen peace deal. In a reminder of the complications of Covid-era travel, he underwent an obligatory quarantine period after returning from his last trip to the Gulf this month. A senior official said that Mr Lenderking's travels were justified by the urgency of relief for Yemen's humanitarian disaster, and because he did not require a large retinue.

State Department officials say that while it may not be ideal, there are benefits to virtual diplomacy. When Mr Blinken spoke by phone last week with the foreign ministers of Australia, India and Japan - who together with the United States make up what is known as the Quad, a group implicitly aligned against China - he was able to connect with counterparts tens of thousands of miles away without disruptive travel time and jet lag.

"Of course, it's always better to be face-to-face with your foreign counterparts. No one wants to live in this world permanently," said Nicholas Burns, a former undersecretary of state and NATO ambassador. But, he added, "it is easier. You can get a lot more done on short order than you did before."

But there are other pitfalls. Journalists will protest a shift to virtual encounters that do not provide the same opportunity for questions that many top-level diplomatic meetings offer.

And then there is the question of keeping video meetings secure. In April, Prime Minister Boris Johnson of Britain tweeted an image of a Zoom meeting over which he was presiding. People were quick to note that the image included the meeting's Zoom ID, potentially allowing uninvited guests to join.

While senior officials like Mr Blinken and Mr Biden rely on methods far more secure than Zoom, they would be wrong to be complacent, Ms Clüver Ashbrook noted.

"We've just come off the biggest hack in American history with SolarWinds," she said. "That should give us pause."