Chinese officials have strongly asserted this summer that no part of the Taiwan Strait can be considered international waters, contrary to the views of the United States and other nations. A Chinese Foreign Ministry spokesman said in June that “China has sovereignty, sovereign rights and jurisdiction over the Taiwan Strait.”

American officials do not know whether China plans to enforce that claim. But Senator Chris Coons of Delaware, who is close to President Biden and deals with the administration often on issues involving Taiwan, said “there is a lot of attention being paid” to what lessons China, its military and Mr. Xi might be learning from events in Ukraine.

“And one school of thought is that the lesson is ‘go early and go strong’ before there is time to strengthen Taiwan’s defenses,” Mr. Coons said in an interview on Sunday. “And we may be heading to an earlier confrontation — more a squeeze than an invasion — than we thought.”

Chinese officials are aware that Biden administration officials, also applying lessons learned from Russia’s invasion of Ukraine, are trying to shape their weapons sales to Taiwan to turn the democratic island into what some call a “porcupine” — bristling with enough effective armaments and defense systems to deter Chinese leaders from trying to attack it.