Washington (CNN) Update: Since we first posted this story, President Trump did weigh in to offer his condolences on the killed sailors.

At the same time, there is another key issue on which the President has not let his voice be heard. During the campaign, he consistently sought to raise awareness about crimes he said were committed by undocumented immigrants.

As President, he has worked to create VOICE, the Victims of Immigrant Crime Engagement Office , specifically to serve the victims of such crimes through the Department of Homeland Security. Opponents have said the effort could unfairly skew public sentiment against the undocumented.

But in Virginia, a Muslim teenager was beaten to death in what authorities say was a case of road rage by an undocumented immigrant. Trump has not yet tweeted about the death of Nabra Hassanen

Original Post from Monday, June 19: President Donald Trump's Twitter feed, for better or worse, has become the single most effective way for him to talk to the American people.

Trump has talked about how the people in his press office -- his paid spokespeople -- can't really be trusted to speak for him since they don't know his latest thinking.

He tweeted Friday that his social media accounts -- with 100 million followers, by his count, if you combine them all together, including the same people using different accounts (an analysis for CNN found his actual number of combined followers is closer to 60 million ) -- are the way he gets around what he calls "the Fake News Media."

"The Fake News Media hates when I use what has turned out to be my very powerful Social Media - over 100 million people! I can go around them."

But Trump's Twitter feed is as powerful in what it doesn't say as what it does. As of noon, the President had tweeted just once Monday — a jam-packed post that did not mention several important issues: seven US sailors killed after their ship's collision with a merchant vessel off Japan's Izu Peninsula, another seven service members wounded in Afghanistan, news of a US Navy jet's downing of a Syrian warplane and a deadly attack on Muslim worshippers on the streets of London.

Throughout the weekend, as these stories broke and developed, his focus — on this most public platform — has been the federal probe he now regularly dismisses as a "witch hunt."

"I am being investigated for firing the FBI Director by the man who told me to fire the FBI Director! Witch Hunt," he tweeted Friday.

You are witnessing the single greatest WITCH HUNT in American political history - led by some very bad and conflicted people! #MAGA — Donald J. Trump (@realDonaldTrump) June 15, 2017

The FAKE MSM is working so hard trying to get me not to use Social Media. They hate that I can get the honest and unfiltered message out. — Donald J. Trump (@realDonaldTrump) June 6, 2017

Trump's attorney, Jay Sekulow, spent the weekend and Monday morning playing cleanup for that admission, arguing on cable news programs that actually the President is not under investigation despite the tweet.

JUST WATCHED Trump lawyer's full heated 'New Day' interview Replay More Videos ... MUST WATCH Trump lawyer's full heated 'New Day' interview 13:55

Since the Friday morning tweet that caused Sekulow so much grief, Trump has used Twitter to tout an online poll that he says shows the American people are behind him, share video of his announcement to roll back aspects of the Obama administration's Cuba policy, say again that he's the victim of a "Witch Hunt," retweet his son's criticism of former President Barack Obama, wish everyone a happy Father's Day, and encourage people in Georgia to vote for Republican Karen Handel in a runoff election Tuesday.

But while Trump's Twitter account has become the way most Americans hear his thoughts, he's not likely to use it to talk about issues that might make him uncomfortable -- unless it is to defend himself in the ongoing investigation by special counsel Robert Mueller into Russia's election meddling and allegations of collusion by Trump campaign officials. That's the "witch hunt," remember.

But there are a few issues on which the Twitter-happy President has notably not chosen to make his voice heard after a busy weekend throughout the world, which he spent at Camp David with his wife and son:

On the developing Finsbury Park attack , in which a van rammed into a crowd of Muslim worshipers after Ramadan prayers in London, the President has so far been silent.

Trump has been quick to weigh in on other terror attacks. Within two hours of the London Bridge attack in early June , Trump was tweeting about it as evidence to justify his travel ban on six majority-Muslim nations. The travel ban is still stymied in the courts. His tweets that morning kicked off a spat between the President of the US and London's mayor.

At other times, Trump has labeled something terrorism even before local authorities. It was not a tweet, but he offered condolences to victims of a mass shooting at a casino in the Philippines, calling it a terrorist attack, and a few minutes later officials in Manila announced it was a robbery.

There are two other important incidents on which Trump might be expected to weigh in, but on which his Twitter account has stayed quiet:

First, he did tweet as the Navy searched for missing sailors after the USS Fitzgerald collided with a much larger container ship flagged to the Philippines, the ACX Crystal, Saturday off the coast of Japan. But he has not tweeted since the Navy announced it had found the bodies of seven sailors who went missing after the accident.

He has also not tweeted about an attack on a military base in Afghanistan that injured seven US service members. That attack is thought to be a "green-on-blue" attack by a member of the Afghan military

Last week, Trump's White House announced in a statement that the President had ceded authority on troop levels in Afghanistan to his secretary of Defense, retired Gen. James Mattis, who is thought to be ready to send between 3,000 and 5,000 additional troops to support US counterterrorism operations against ISIS and the Taliban. Trump has also delegated that authority to Mattis for Iraq and Syria, where the US is fighting ISIS.

Beyond not tweeting about the attack on US service members or his decision to delegate authority on troop levels, Trump has also not tweeted on a situation in Syria that could potentially spiral into an air war with Syria — and potentially Russia.

If Twitter is indeed Trump's preferred method for engaging with the public, a note — something! — on these matters of life and death, war and peace, might be welcome ... and soon.