To the Editor:

Re “Trump Tied Aid to Inquiries, Envoy Says” (front page, Oct. 23):

Great moments in human history are better than the best fiction, and they often turn on the contributions of unexpected participants.

The contribution of one Vasily Arkhipov to the future of humanity may never be equaled. He was a senior officer on a Soviet sub during the Cuban Missile Crisis in 1962 and refused to assent to Capt. Valentin Savitsky ’s desire to launch a nuclear weapon , which could have ignited global thermonuclear war. (Though this was not known to us for decades, there ought to be statues of him throughout the world.)

Tuesday was another one of those moments for a lesser-known figure to have an indelible impact.

William Taylor — the top American diplomat in Ukraine and the very model of a lifelong, bipartisan public servant of the highest character — presented detailed testimony that is a searing indictment of the president of the United States. Now, no member of Congress can reasonably argue that there are no grounds for impeachment and removal from office.

Mark Keller

Portland, Ore.

To the Editor:

The improper pressure on the Ukrainian government and on William Taylor was intended in part to discredit the Russia investigation done by the American intelligence agencies, and thereby to reproach and threaten those who would dare to investigate President Trump. The professionals of the State Department have pushed back against this pressure, forcefully.