But there was little doubt that his marathon of diplomacy in Asia would continue unaltered -- a sign that increasingly deadly shooting sprees have become a standard aspect of the presidential routine that no longer merit a break from regular order.
Sunday's church massacre
took place in Sutherland Springs, Texas. In addition to the at least 26 people who were killed, at least 20 others were wounded -- the victims ranging in age from 5 to 72 years old.
Among the dead is the 14-year-old daughter of the church's pastor, Frank Pomeroy, according to his wife, Sherri Pomeroy, the girl's mother. The couple were traveling out of state when the shooting occurred.
As President, Trump has now witnessed two of the five deadliest shootings in modern US history -- all within the last 35 days
. Like presidents before him, Trump is finding his own way of confronting the type of mass gun violence that is unique to the United States among other wealthy nations.
Trump's is an approach that largely discounts the ability of legislators or the government to prevent the brutal killings that have now claimed hundreds of lives under his presidency. It's a sharp break from his predecessor, who over his eight-year presidency assumed an increasingly frustrated tone at lawmakers' inability to approve meaningful gun control legislation.
Even as Trump criss-crosses Asia on a mission to combat a nuclear threat from North Korea, he's offered few tangible solutions to the gun violence outbreak that's killing Americans daily.
"Mental health is your problem here," Trump said during remarks in a news conference in Tokyo, noting that "based on preliminary reports" the shooter was "a very deranged individual."
"This isn't a guns situation," Trump said. "This is a mental health problem at the highest level. It's a very, very sad event."
Following last month's attack at a country music festival in Las Vegas, Trump similarly questioned the shooter's mental state but expressed a fleeting openness to a discussion of legislation that would ban sales of so-called "bump stocks" which make firing rounds faster.
But a month later that discussion hasn't yet materialized
-- and with major legislative battles over tax reform and immigration looming, it seems unlikely that Congress will take up the matter in the near-term.
That Trump was in Japan, where personal gun ownership is virtually outlawed and deaths by firearm are among the lowest in the world, only placed the US situation in sharper relief.
There were six gun deaths in Japan in 2014, national statistics show -- less than one-quarter of the number who were killed Sunday in Texas alone. The same year in the US saw 33,599 deaths by guns.
Like citizens of most other countries, Japanese are confounded by America's rash of mass shootings, as foreign an epidemic as bubonic plague.
Trump has taken a variety of positions on gun control over his decades in the public eye. He supported a ban on assault weapons and called for greater restrictions on firearms after the 2012 shooting at the Sandy Hook elementary school in Connecticut.
But since becoming a Republican politician he's largely assumed the party's strict opposition to new measures that would make it more difficult to buy a gun.
Speaking at this year's annual National Rifle Association meeting
, he declared an "eight-year assault on the Second Amendment is over."